Photo: “tail light” by John Eric Eudin, (CC BY-ND 2.0) http://tinyurl.com/ndp3cbj
On Monday, the US Supreme Court decided that it does not violate the Fourth Amendment for the police to seize evidence after detaining a person for legal behavior that they mistakenly thought was illegal. At issue in Heien v. North Carolina was the admissibility of cocaine found by the police in a car stopped for a traffic violation. The arresting officer became suspicious because he thought the driver looked unusually stiff and nervous. He stopped the car for only having one functioning brake light, which, it turns out, is perfectly legal in North Carolina.
Chief Justice Roberts writing for the majority concluded that there was no violation of the Fourth Amendment as long as the police officer’s mistake of law was reasonable. Justice Sotomayor dissented. She wrote that unlike the foggy world of factual determinations, the law is definite and knowable. It is an unnecessary erosion of civil liberties to authorize police to conduct seizures where the only justification for the detention is their plausible though incorrect understanding of the law.
Canadian courts have dealt with this issue and concluded that an arrest for a non-existent offence is arbitrary and a constitutional violation. However, evidence seized as a result of the arbitrary arrest can be admitted anyway if its admission wouldn’t bring the administration of justice into disrepute. The Canadian approach at least has the merit of putting the police on notice that such mistakes take them outside their lawful police powers, even if the practical consequence in a given case is limited. It also imposes a responsibility on future courts to adjust the s. 24(2) remedy to reflect the diminishing weight of law enforcement claims that ignorance of the law is reasonable.
There is a certain irony in the fact that reasonable mistake of law is not an excuse that can be raised by a defendant, but that such a mistake can excuse overreach by the very professionals trained to know and enforce the law.