In our last post, we began exploring the issue of mistakes of law and mistakes of fact in criminal investigations, connecting our discussion to the Freddie Gray case. As we’ve mentioned, officers were under the mistaken belief that the knife Gray had been carrying was illegal when it actually was not.
Mistakes of fact can happen in criminal investigations, without doubt. One well-established principle of criminal law is that a factual mistake does not invalidate a search warrant that would have been valid if the factual mistake was made in good faith, meaning that it was not intentional. Obviously, though, if an officer lies about the facts in order to obtain a warrant, this is illegal. When there is simply a reasonable mistake of fact, though, the warrant is still valid.
In other words, reasonable mistakes regarding the facts do not vitiate a police investigation. In addition, a fairly recent Supreme Court case recognized that reasonable mistakes of law do not violate the Fourth Amendment. In that case, the issue was whether an officer’s mistaken understanding of the law made his traffic stop and a subsequent vehicle search unreasonable, since a correct understanding of the law would not have led to the traffic stop.
So, reasonable mistakes regarding the facts and the law do not necessarily invalidate police searches and seizures. It is important for criminal defendants to explore the issue with an experienced criminal defense attorney, though, since the reasonableness of a search may be subject to dispute. When it is, having an advocate is critical.