In Heien, the United States Supreme Court considered a police officer’s reasonable but erroneous interpretation of a motor vehicle statute. Chief Justice Roberts’s majority opinion noted that “the ultimate touchstone of the Fourth Amendment is ‘reasonableness.'” After explaining that “[t]o be reasonable is not to be perfect,” and that the Fourth Amendment allows for reasonable mistakes of fact, the Chief Justice went on to explain that the Fourth Amendment reasonableness inquiry applies to mistakes of law just as it applies to mistakes of fact. Based on the language of the North Carolina statute involved in Heien, Chief Justice Roberts concluded that the officer’s error of law was reasonable and thus provided the officer with reasonable suspicion to justify the traffic stop. Importantly, Justice Kagan, joined by Justice Ginsburg, wrote a concurrence that has garnered support with states that have chosen to follow the Heien approach in their own search and seizure analyses. Critical to her agreement with the majority was her belief that erroneous interpretations of the law will pass Fourth Amendment scrutiny only when the law at issue is “‘so doubtful in construction’ that a reasonable judge could agree with the officer’s view.” Such cases must necessarily involve a “really difficult” or “very hard question of statutory interpretation” and will thus be “exceedingly rare.”
It can be argued that our courts should also not permit a reasonable mistake of law to justify a search or seizure. The rationale behind suppressing evidence in cases like Sutherland’s is to encourage the police to know the law that they enforce, i.e. to let the police know that they are wasting time and resources when they conduct searches or seizures without an awareness of the statutory basis to do so. Since Heien’s mistake of law exception applies in cases where the Legislature drafted ambiguous statutes, and we want to deter the Legislature from being sloppy with the drafting of their statutes, suppression of evidence would also make sense in those “exceedingly rare” cases where a stop is based on a poorly-worded statute. Put another way, it is also important to deter the Legislature from wasting time and resources.