Police cannot be sued for mistakenly arresting a man whose name isidentical to someone else’s on an outstanding warrant — even if the first man’s addressand date of birth are different — as long as the officers had a “reasonable good-faithbelief” that they had captured the right man, a federal judge has ruled. In his 12-page opinion in Alvin Grant v. Borough of Darby, Senior U.S. District JudgeThomas N. O’Neill found that while the Fourth Amendment prohibits unreasonable searchesand seizures, it “does not guarantee that only the guilty will be arrested.”

A police officer making an arrest pursuant to a facially valid warrant “has no obligationto investigate independently every claim of innocence, whether the claim is based onmistaken identity or otherwise,” O’Neill wrote.