The Supreme Court has long held that a police officer’s reasonable mistake of fact may give rise to a lawful search or seizure under the Fourth Amendment.^1×1. See, e.g., Illinois v. Rodriguez, 497 U.S. 177, 185–86 (1990) (“[W]hat is generally demanded of the many factual determinations that must regularly be made by agents of the government . . . is not that they always be correct, but that they always be reasonable.”); Hill v. California, 401 U.S. 797, 804–05 (1971); Brinegar v. United States, 338 U.S. 160, 176 (1949). But where an officer acts upon a reasonable mistake of law, lower courts have differed on whether the corresponding search or seizure encroaches upon constitutional rights.^2×2. Compare, e.g., United States v. Martin, 411 F.3d 998, 1001 (8th Cir. 2005) (search or seizure may be lawful if mistake of law reasonable), with United States v. Chanthasouxat, 342 F.3d 1271, 1279 (11th Cir. 2003) (traffic stop based on mistake of law never lawful). Last Term, in Heien v. North Carolina,^3×3. 135 S. Ct. 530 (2014). the Supreme Court held that a police officer’s reasonable mistake of law may give rise to the reasonable suspicion needed to justify a traffic stop under the Fourth Amendment.^4×4. Id. at 534. Mindful that an open-ended “reasonableness” test might sow confusion — or worse, abuse — both the majority and concurrence sought to cabin the reasonable-mistake-of-law test with additional qualifiers. Such qualifiers allay some but not all concerns over what the Heien test means for judicial administrability and police discretion.

Heien arose out of a routine traffic stop. In April 2009, Sergeant Matt Darisse of the Surry County Sheriff’s Department was patrolling traffic when a Ford Escort passed by.^5×5. Id. The driver’s “stiff and nervous” demeanor aroused the officer’s suspicions, prompting him to follow.^6×6. Id. After a few miles, Darisse noticed that the Escort’s right rear brake light didn’t illuminate when triggered.^7×7. Id. On the belief that state law required two functioning brake lights, he stopped the car with its two passengers: the driver, Maynor Javier Vasquez, and the owner, Nicholas Brady Heien.^8×8. See id. Once Darisse confirmed that Vasquez possessed valid license and registration, he issued a warning ticket.^9×9. Id. But Darisse did not leave. Dubious after the men reported inconsistent destinations,^10×10. Vasquez said they were driving to West Virginia, while Heien averred that their destination was Kentucky. State v. Heien, 737 S.E.2d 351, 352 (N.C. 2012). he asked for and obtained permission to search the car.^11×11. Heien, 135 S. Ct. at 534. His search turned up a sandwich bag of cocaine.^12×12. Id.

Charged with attempted trafficking in cocaine, Heien moved to suppress the evidence obtained from the search, arguing that it flowed from an illegal stop.^13×13. Id. at 535. Heien pled guilty, but reserved the right to appeal the denial of his motion to suppress. Id. The trial court refused on the grounds that Darisse had reasonable suspicion to effectuate his seizure under the Fourth Amendment.^14×14. Heien, 737 S.E.2d at 353.

The North Carolina Court of Appeals reversed.^15×15. State v. Heien, 714 S.E.2d 827, 831 (N.C. Ct. App. 2011). In its view, a stop is not objectively reasonable when predicated upon an error of law.^16×16. Id. at 829. Because the state vehicle code referred several times to a “stop lamp” in the singular, the court interpreted the law as requiring only one working brake light.^17×17. Id. The court found other sections of the state code equally unavailing for the officer. See id. at 830–31. On that reading, Darisse lacked reasonable suspicion for stopping Heien.^18×18. Id. at 831.

The North Carolina Supreme Court reversed.^19×19. Heien, 737 S.E.2d at 359. Three of the seven justices dissented. Though the state did not seek review of the lower court’s interpretation of the vehicle code,^20×20. Id. at 354. the court nonetheless upheld Darisse’s stop.^21×21. Id. at 352. It framed its analysis as a choice between one federal circuit’s position that a mistake of law could never give rise to reasonable suspicion^22×22. Id. at 355–56 (discussing United States v. Chanthasouxat, 342 F.3d 1271 (11th Cir. 2003)). and another circuit’s requirement that police mistakes of law simply be reason-able.^23×23. Id. (discussing United States v. Martin, 411 F.3d 998 (8th Cir. 2005)). The court embraced the latter view, believing that it would promote safer roadways^24×24. Id. at 357. and better comport “with the primary command of the Fourth Amendment — that law enforcement agents act reasonably.”^25×25. Id. at 356. The North Carolina Supreme Court then remanded to the state’s Court of Appeals to deal with Heien’s other arguments. The lower court rejected those arguments and affirmed the trial court’s denial of Heien’s motion to suppress, and the North Carolina Supreme Court did the same. Heien, 135 S. Ct. at 535.

The Supreme Court affirmed.^26×26. Heien, 135 S. Ct. at 534. Writing for the Court, Chief Justice Roberts^27×27. Chief Justice Roberts was joined by every member of the Court save Justice Sotomayor. opened with the oft-cited proposition that “the ultimate touchstone of the Fourth Amendment is ‘reasonableness.’”^28×28. Heien, 135 S. Ct. at 536 (quoting Riley v. California, 134 S. Ct. 2473, 2482 (2014)). But “[t]o be reasonable is not to be perfect.”^29×29. Id. Just as the Court has “recognized that searches and seizures based on mistakes of fact can be reasonable,”^30×30. Id. In Illinois v. Rodriguez, 497 U.S. 177 (1990), the Court sanctioned a home search even though the source of the consent was a nonresident. Id. at 179. Because the officer’s mistake of identity was reasonable, the corresponding search was too. Id. at 186–89. the Chief Justice reasoned, it should do the same for mistakes of law.^31×31. Heien, 135 S. Ct. at 536 (“Whether the facts turn out to be not what was thought, or the law turns out to be not what was thought, the result is the same: the facts are outside the scope of the law.”).

For support, the Court looked first to cases arising out of an early statute indemnifying customs officers against unlawful-seizure suits.^32×32. Id. at 536–37. In United States v. Riddle,^33×33. 9 U.S. (5 Cranch) 311 (1809). Chief Justice Marshall affirmed the issuance of a probable cause certificate for an officer who had seized En-glish goods based on a reasonable but mistaken reading of the statute.^34×34. Id. at 313. “A doubt as to the true construction of the law is as reasonable a cause for seizure as a doubt respecting the fact,” he pronounced.^35×35. Heien, 135 S. Ct. at 537 (quoting Riddle, 9 U.S. (5 Cranch) at 313). The Chief Justice acknowledged that Riddle and later cases were not Fourth Amendment cases and so not “directly on point.” Id. But he maintained that they were relevant because probable cause has always had a “fixed and well known meaning,” id. (quoting Locke v. United States, 11 (7 Cranch) 339, 348 (1813)), that has always “encompassed suspicion based on reasonable mistakes of both fact and law,” id.

The Court turned next to Michigan v. DeFillippo,^36×36. 443 U.S. 31 (1979). a decision that both parties’ briefs discussed at some length.^37×37. See Brief for Petitioner at 27–29, 35, Heien, 135 S. Ct. 530 (No. 13-604); Brief for the Respondent at 8, 18, 19, 30, Heien, 135 S. Ct. 530 (No. 13-604). In that case, an officer found drugs on DeFillippo while arresting him for violating a city ordinance that was later held unconstitutional.^38×38. DeFillippo, 443 U.S. at 33–34. In the Court’s retelling, the DeFillippo Court held that the search was nevertheless lawful because at the time of arrest, the ordinance was “presumptively valid”;^39×39. Heien, 135 S. Ct. at 538 (quoting DeFillippo, 443 U.S. at 37). the officer’s mistake was in that sense understandable, providing “abundant probable cause” for an arrest.^40×40. Id. (quoting DeFillippo, 443 U.S. at 37). Though Heien “struggle[d] to recast DeFillippo as a case solely about the exclusionary rule,”^41×41. Id. the case clearly went to the heart of the Fourth Amendment itself.^42×42. Because North Carolina does not recognize a good-faith exception to the exclusionary rule, see State v. Carter, 370 S.E.2d 553, 560–62 (N.C. 1988); see also Heien, 135 S. Ct. at 545 (Sotomayor, J., dissenting), a holding that Sergeant Darisse’s actions had violated Heien’s Fourth Amendment rights would have resulted in the cocaine being suppressed.

The Court then considered three of Heien’s other claims. Responding first to the contention that unlike with legal judgments “[o]fficers in the field must make factual assessments on the fly,” the majority argued that in many instances an officer would have to quickly resolve legal ambiguities in the field as well.^43×43. Heien, 135 S. Ct. at 538. Adding color to this point, the Chief Justice gave this example: “A law prohibiting ‘vehicles’ in the park either covers Segways or not, but an officer will nevertheless have to make a quick decision on the law the first time one whizzes by.” Id. (citation omitted) (citing Antonin Scalia & Bryan A. Garner, Reading Law: The Interpretation of Legal Texts 36–38 (2012)). Second, the Court’s rule would “not discourage officers from learning the law,” for the “Fourth Amendment tolerates only . . . objectively reasonable” mistakes, an “inquiry . . . not as forgiving” as the one used in the qualified immunity context, and one that would not reward “sloppy study of the laws.”^44×44. Id. at 539–40. Third, in response to the argument that it would be unjust to permit officers but not citizens to make errors of law, the Court countered that “just because mistakes of law cannot justify either the imposition or the avoidance of criminal liability, it does not follow that they cannot justify an investigatory stop.”^45×45. Id. at 540. After all, Heien was charged for a drug crime, not a mistaken traffic violation. See id.

Having decided that a reasonable mistake of law may justify a stop, the Chief Justice concluded with “little difficulty” that Sergeant Darisse’s mistake of law was objectively reasonable.^46×46. Id. He relied on two provisions of the state statute: one providing that “[t]he stop lamp may be incorporated into a unit with one or more other rear lamps,”^47×47. N.C. Gen. Stat. § 20-129(g) (2013) (emphasis added). which “suggests to the everyday reader of English that a ‘stop lamp’ is a type of ‘rear lamp,’”^48×48. Heien, 135 S. Ct. at 540. and the other requiring vehicles to “have all originally equipped rear lamps or the equivalent in good working order.”^49×49. N.C. Gen. Stat. § 20-129(d). Read together, these provisions could reasonably appear to require two working brake lights.^50×50. Heien, 135 S. Ct. at 540. Under the lodestar of “reasonableness,” Sergeant Darisse committed no Fourth Amendment violation.

Justice Kagan concurred^51×51. Justice Kagan was joined by Justice Ginsburg. to highlight two points: First, “an officer’s ‘subjective understanding’ is irrelevant” to the reasonableness inquiry, meaning that a lack of training or awareness of the law “cannot help to justify a seizure.”^52×52. Heien, 135 S. Ct. at 541 (Kagan, J., concurring). Second, the Court’s test “is more demanding” than what is required under qualified immunity.^53×53. Id. The latter protects “all but the plainly incompetent or those who knowingly violate the law,”^54×54. Id. (quoting Ashcroft v. al-Kidd, 131 S. Ct. 2074, 2085 (2011)). whereas a court applying Heien “faces a straightforward question of statutory construction” — “[i]f the statute is genuinely ambiguous, such that overturning the officer’s judgment requires hard interpretive work, then the officer has made a reasonable mistake.”^55×55. Id. The statute must pose a “very hard question of statutory interpretation,”^56×56. Id. (quoting Transcript of Oral Argument at 50, Heien, 135 S. Ct. 530 (No. 13-604)). and such cases would be “exceedingly rare.”^57×57. Id. (quoting Brief for the Respondent, supra note 37, at 17; Transcript of Oral Argument, supra note 56, at 48).

Justice Sotomayor, the lone dissenter, would have adopted a rule “evaluating an officer’s understanding of the facts against the actual state of the law.”^58×58. Id. at 542 (Sotomayor, J., dissenting). Though the “ultimate touchstone of the Fourth Amendment is ‘reasonableness,’” she wrote, id. (quoting Riley v. California, 134 S. Ct. 2473, 2482 (2014)), that broad principle “does not define the categories of inputs that courts are to consider when assessing the reasonableness of a search or seizure, each of which must be independently justified,” id. In canvassing the Court’s major probable-cause precedents, she found “scarcely a peep” on anything other than mistakes of fact.^59×59. Id. at 543. This silence was unsurprising, the Justice explained, as officers must make “quick decisions” in the field, enjoying relative expertise as factfinders.^60×60. Id. But legal meanings are not “probabilistic” like factual determinations, and courts — not officers — enjoy comparative expertise in “legal exegesis.”^61×61. Id.

Heien’s holding, the dissent warned, “further erod[es] the Fourth Amendment’s protection of civil liberties.”^62×62. Id. When the Court permitted pretextual searches in Whren v. United States,^63×63. 517 U.S. 806 (1996). it assumed that “[the] pretext would be the violation of an actual law.”^64×64. Heien, 135 S. Ct. at 543 (Sotomayor, J., dissenting). But if the police have “license to effect seizures so long as they can attach to their reasonable view of the facts some reasonable legal interpretation (or misinterpretation),”^65×65. Id. innocent citizens will face great difficulty in trying “to avoid . . . invasive, frightening, and humiliating encounters.”^66×66. Id. at 544.

Turning to the majority’s reasoning, the dissent questioned the relevance of founding-era customs statutes^67×67. Id. at 545. and criticized the Chief Justice’s treatment of DeFillippo for “imagin[ing] a holding . . . not rooted in the logic of the opinion.”^68×68. Id. at 546. On the dissent’s reading, DeFillippo “did not involve any police ‘mistake’ at all,” and so could not be said to control.^69×69. Id. Finally, while acknowledging the concurrence’s efforts to “set some bounds” on the scope of the Court’s test, Justice Sotomayor predicted that it would “prove murky in application.”^70×70. Id. at 547.

Taken together, the majority and concurrence’s “reasonableness” guidance can be reduced to three points: (1) the inquiry is objective;^71×71. Id. at 539 (majority opinion); see also id. at 541 (Kagan, J., concurring). (2) it is “not as forgiving” as the qualified immunity standard;^72×72. Id. at 539 (majority opinion); see also id. at 541 (Kagan, J., concurring). and (3) a mistake is reasonable when the statute is “genuinely ambiguous”^73×73. Id. at 541 (Kagan, J., concurring). or, in other words, “‘so doubtful in construction’ that a reasonable judge could agree with the officer’s view.”^74×74. Id. (quoting The Friendship, 9 F. Cas. 825, 826 (C.C.D. Mass. 1812) (No. 5,125)). This third point did not command a majority of the Court. Though cabined in these ways, the Heien test is less restrictive than first meets the eye. The leeway afforded to officer mistakes of law may ultimately prove quite broad.

First, the Court failed to appreciate the dangers of abandoning a subjective inquiry. In defending the Court’s holding, Chief Justice Roberts pointed out that an objective standard would ensure that “an officer can gain no Fourth Amendment advantage through a sloppy study of the laws.”^75×75. Id. at 539–40 (majority opinion). Justice Kagan concurred on this point, writing that the objective approach would not forgive “an officer’s mistaken legal interpretation on the ground that the officer was unaware of or untrained in the law.” Id. at 541 (Kagan, J., concurring). But the objective approach cuts both ways. While it does not condone ignorance of the laws, it also does not prevent officers from leveraging legal uncertainty in ways that can be equally perverse. Consider a traffic code with an ambiguous provision susceptible to several reasonable interpretations. Under the Heien test, an enterprising officer might conduct searches and seizures based on violations under any of those interpretations, even if they conflict. In United States v. McDonald,^76×76. 453 F.3d 958 (7th Cir. 2006). Illinois traffic law did not indicate whether turning on a ninety-degree curve on a road that changed names required use of a turn signal, or whether using a signal was even legal.^77×77. Id. at 959–60; see also Brief for Petitioner, supra note 37, at 42. But because one might reasonably interpret statutory silence as either requiring or forbidding a turn signal, an officer confronting a similar statute might simply wait and see which course a driver followed before apprehending her on the reasonable belief that she had violated the law.^78×78. See Brief for Petitioner, supra note 37, at 42. In McDonald, the officer had stopped McDonald for using his turn signal when going around the ninety-degree bend. McDonald, 453 F.3d at 959. The Seventh Circuit held that the law did not prohibit such an action, and that the officer’s mistake of law could not justify the stop. Id. at 961–62.

The Court’s objective test is underrestrictive for another reason: by injecting knotty questions of statutory interpretation into Fourth Amendment analysis, the Court may also have imported divisive debates over interpretive theory that polarize even the most “reasonable” jurists and scholars.^79×79. For a flavor of one such debate, see Robert A. Katzmann, Judging Statutes 29–54 (2014) (summarizing the textualism versus purposivism divide); John F. Manning, What Divides Textualists from Purposivists?, 106 Colum. L. Rev. 70 (2006). The likely effect will be to bring a whole range of interpretations under the “reasonableness” umbrella. If intelligent readings of text, structure, and purpose can lead to multiple, contested outcomes when deciding the “correct” interpretation, an even larger range of readings will emerge when the standard is relaxed to admit mere “reasonable” interpretations.

Imperfect analogies from other contexts bear this point out. When courts are asked to carry out Step Two of the Chevron test, which mandates judicial deference to “reasonable” agency interpretations of ambiguous statutes,^80×80. See Chevron U.S.A. Inc. v. Nat. Res. Def. Council, Inc., 467 U.S. 837, 842–44 (1984). such interpretations are accorded a “wide berth.”^81×81. Nat’l Ass’n of Regulatory Util. Comm’rs v. ICC, 41 F.3d 721, 728 (D.C. Cir. 1994). Accordingly, courts have only rarely bucked the agency interpretation at Step Two, often sustaining it “in a perfunctory way.”^82×82. M. Elizabeth Magill, Step Two of Chevron v. Natural Resources Defense Council, in A Guide to Judicial and Political Review of Federal Agencies 85, 86 (John F. Duffy & Michael Herz eds., 2005) (finding Chevron Step Two invalidations to be “extremely rare”); see also Ronald M. Levin, The Anatomy of Chevron: Step Two Reconsidered, 72 Chi.-Kent L. Rev. 1253, 1261 (1997) (“[I]n the thirteen years since Chevron, the Court has never once struck down an agency’s interpretation by relying squarely on the second Chevron step.” (emphasis omitted)). Heien, of course, is not a doctrine of deference, and it does not share Chevron’s background assumption that legislatures intend for agencies to resolve statutory ambiguities.^83×83. See Cass R. Sunstein, Chevron Step Zero, 92 Va. L. Rev. 187, 189 (2006) (“Chevron seemed to declare that in the face of ambiguity, it is emphatically the province and duty of the administrative department to say what the law is.”). But having received minimal guidance as to what an objectively reasonable mistake of law entails, lower courts might be forgiven for mistakenly (if not reasonably) letting Chevron-grade deference seep into their Heien-rule decisionmaking.

Anticipating, perhaps, that lower courts might need more than the language of objective reasonableness, the Court clarified that its test would be more exacting than the one associated with qualified immunity — a doctrine that protects government officials from civil liability.^84×84. Qualified immunity may come into play in “Bivens” suits against federal actors, named after Bivens v. Six Unknown Named Agents of Federal Bureau of Narcotics, 403 U.S. 388 (1971), or suits against state actors under 42 U.S.C. § 1983. See Gary S. Gildin, The Standard of Culpability in Section 1983 and Bivens Actions: The Prima Facie Case, Qualified Immunity and the Constitution, 11 Hofstra L. Rev. 557, 557–59 (1983). Qualified immunity, as stated succinctly in Harlow v. Fitzgerald,^85×85. 457 U.S. 800 (1982). shields “government officials performing discretionary functions . . . from liability for civil damages insofar as their conduct does not violate clearly established statutory or constitutional rights of which a reasonable person would have known.”^86×86. Id. at 818.

The reference to qualified immunity does not meaningfully limit Heien. First, though both tests require objective analysis, the inquiries are distinct. In applying Harlow, courts have focused not on basic questions of statutory or constitutional interpretation, but instead on ascertaining whether a right was “clearly established.”^87×87. Id. In the circuit courts, the “dominant method is simply to count — are there enough decisions to tell an official that his action is unconstitutional?”^88×88. John C. Williams, Note, Qualifying Qualified Immunity, 65 Vand. L. Rev. 1295, 1323 (2012). The author calls this approach “wrongheaded.” Id. Though this method is “objective” in that it asks what a hypothetical reasonable official should know, it has become a wholly separate kind of analysis from Heien’s question of statutory interpretation.

Second, qualified immunity doctrine can be so protective of official conduct that it does not mean much as a conceptual baseline. As Justice Scalia asserted in Ashcroft v. al-Kidd,^89×89. 131 S. Ct. 2074 (2011). “[w]hen properly applied, [qualified immunity] protects ‘all but the plainly incompetent or those who knowingly violate the law.’”^90×90. Id. at 2085 (quoting Malley v. Briggs, 475 U.S. 335, 341 (1986)). Addressing Heien’s fear that this standard might come to govern police mistakes of law,^91×91. See Brief for Petitioner, supra note 37, at 41–42. Justice Kagan dismissed it as not part of the Court’s test.^92×92. See Heien, 135 S. Ct. at 540–41 (Kagan, J., concurring). Though reassuring as an upper bound, it also adds very little. “Reasonable” interpretations of law do not tend to issue from officials of “plain incompetence,” and the Heien test does not penalize those who “knowingly violate the law” for gaining advantage from ambiguity, as explained above.

Though Justice Kagan’s concurrence sought to more clearly delineate the scope of the Court’s “reasonableness” inquiry, its impact may also be limited. First, and most importantly, Justices Kagan and Ginsburg did not speak for the Court — their two votes were not needed to sustain the majority’s position. Whether the other Justices thought the concurrence misguided or simply unnecessary, a lower court might justifiably question why its reasoning attracted only two votes.^93×93. This is not to suggest that concurrences can never be influential. See, e.g., Katz v. United States, 389 U.S. 347, 360–62 (1967) (Harlan, J., concurring); Youngstown Sheet & Tube Co. v. Sawyer, 343 U.S. 579, 634–55 (1952) (Jackson, J., concurring).

Second, even if a lower court did give effect to Justice Kagan’s qualifiers, it is not clear what they would entail. Superficially, they recall Chevron deference,^94×94. Under Justice Stevens’s canonical formulation of the test, a court reviewing an agency’s interpretation of a statute the agency administers asks first whether the statutory language is clear. Chevron U.S.A. Inc. v. Nat. Res. Def. Council, Inc., 467 U.S. 837, 842–43 (1984). If, in “employing traditional tools of statutory construction, [the court] ascertains that Congress had an intention on the precise question at issue, that intention is the law and must be given effect.” Id. at 843 n.9. But “if the statute is silent or ambiguous,” the analysis proceeds to Step Two, which asks “whether the agency’s answer is based on a permissible construction of the statute.” Id. at 843. asking that courts sustain reasonable interpretations in cases of ambiguity.^95×95. See Heien, 135 S. Ct. at 541 (Kagan, J., concurring). Justice Kagan noted that this threshold step of gauging whether a statute is ambiguous would require answering “a straightforward question of statutory construction,” id., presumably requiring the same “traditional tools of statutory construction” used in Chevron, 467 U.S. at 843 n.9. But if Chevron is any guide, courts are likely to find ambiguity far more often than the concurrence suggests. In a recent empirical analysis, Professor Richard Re examined all federal appellate court decisions in 2011 that cited Chevron, finding that the courts reached Step Two — that is, found the statute ambiguous — in 79 of 110 cases. Richard M. Re, Should Chevron Have Two Steps?, 89 Ind. L.J. 605, 638–39 (2014). But because Heien does not share Chevron’s background delegation assumptions, closer analogies may be found in the rule of lenity or the canon of constitutional avoidance, both of which ask judges to adopt alternate plausible interpretations in the face of ambiguity.^96×96. See Ward Farnsworth, Dustin F. Guzior & Anup Malani, Ambiguity About Ambiguity: An Empirical Inquiry into Legal Interpretation, 2 J. Legal Analysis 257, 258 (2010). Although not limited to laws involving a delegation to an agency, these other ambiguity canons seem to arise on more than the “exceedingly rare”^97×97. Heien, 135 S. Ct. at 541 (Kagan, J., concurring) (quoting Brief for the Respondent, supra note 37, at 17; Transcript of Oral Argument, supra note 56, at 48). occasion.

But on top of familiar standards like “genuine ambiguity,” the concurrence affixed superlative terms like “really difficult” or “very hard question of statutory interpretation” to further cabin Heien’s scope.^98×98. Id. (quoting Transcript of Oral Argument, supra note 56, at 50). Though reassuring on the surface, the concurrence offered little guidance as to what “very hard” or “really difficult” actually mean. In practice, the difficulty of resolving a question of statutory interpretation can often depend entirely on one’s preferred interpretive approach. To take an example from this Term, in King v. Burwell,^99×99. 135 S. Ct. 2480 (2015); see also Abbe R. Gluck, The Supreme Court, 2014 Term — Comment: Imperfect Statutes, Imperfect Courts: Understanding Congress’s Plan in the Era of Unorthodox Lawmaking, 129 Harv. L. Rev. 62 (2015). the Court found a short provision of the Patient Protection and Affordable Care Act^100×100. Pub. L. No. 111-148, 124 Stat. 119 (2010) (codified as amended in scattered sections of the U.S. Code). to be “properly viewed as ambiguous,”^101×101. King, 135 S. Ct. at 2491. while the dissent thought the contrary reading “absurd”^102×102. Id. at 2496 (Scalia, J., dissenting). and a “defense of the indefensible.”^103×103. Id. at 2502. The majority and dissent disagreed profoundly as to not only which reading was right, but also how hard it was to answer the underlying interpretive question.^104×104. That disagreement depended in turn on how much each jurist valued text, structure, and purpose. For an overview of the interpretive debate, see sources cited supra note 79. Cases like King cast greater doubt on the prediction that very hard cases of interpretation will be “exceedingly rare.”

Justice Kagan added that “really difficult” questions would be ones “‘so doubtful in construction’ that a reasonable judge could agree with the officer’s view.”^105×105. Heien, 135 S. Ct. at 541 (Kagan, J., concurring) (quoting The Friendship, 9 F. Cas. 825, 826 (C.C.D. Mass. 1812) (No. 5,125)). But this may relax the test even more. A reviewing court may be even less likely to overrule a police officer’s mistaken legal interpretation after lower courts have accepted that reading of the law as “reasonable” — as they did in Heien.^106×106. See State v. Heien, 737 S.E.2d 351, 353 (N.C. 2012). Overruling officer interpretations under these circumstances would suggest that a fellow jurist was not only incorrect, but also “unreasonable,” implying a serious deficiency in the judge’s legal competence and character. Indeed, in other contexts, courts have shown a high level of comity to lower courts accused of making “unreasonable” legal interpretations.^107×107. One provision of the Antiterrorism and Effective Death Penalty Act of 1996 (AEDPA), Pub. L. No. 104-132, 110 Stat. 1214 (codified as amended in scattered sections of the U.S. Code), lets federal courts issue relief when state court rulings are based on an “unreasonable application of[] clearly established Federal law.” 28 U.S.C. § 2254(d)(1) (2012). But the Court has limited this power to cases where “there is no possibility fairminded jurists could disagree that the state court’s decision conflicts with [the Supreme] Court’s precedents.” Harrington v. Richter, 131 S. Ct. 770, 786 (2011). Under this standard, and out of comity, the Court has “consistently uph[eld] erroneous state court decisions” in AEDPA proceedings. Stephen R. Reinhardt, The Demise of Habeas Corpus and the Rise of Qualified Immunity: The Court’s Ever Increasing Limitations on the Development and Enforcement of Constitutional Rights and Some Particularly Unfortunate Consequences, 113 Mich. L. Rev. 1219, 1221 n.8 (2015); id. (listing cases).

The concurrence may have used words like “very hard” and “really difficult” to try and limit reasonable mistakes to those as forgivable as Sergeant Darisse’s misinterpretation of the vehicle code. Between the use of the plural and the juxtaposition of “stop lamp” and “rear lamp,” one might have easily arrived at two equally reasonable readings of the statute. In that sense, Heien was the perfect case for supporters of the majority’s approach, as it forced the Court to confront not just a reasonable, but an extremely reasonable — some would say even correct — interpretation of the law. The concurrence sought to cabin its rule to only those clear cases, but for the reasons highlighted above, its guidance may fall short of this goal. If that happens, the result will be more officer discretion, and in some cases, abuse.