Welsh v. Wisconsin

Before officers may invade the sanctity of the home, the government must demonstrate exigent circumstances that overcome the presumption of unreasonableness that is inherent in all warrantless entries. An important factor to be considered is the gravity of the underlying offense for which the arrest is being made. Probable cause to believe that a serious crime has been committed does not, by itself, create an exigency. Even a finding of an exigency rarely sanctions an intrusion if only a minor offense has been committed.

The defendant’s warrantless arrest in his home for a non-criminal traffic offense cannot be justified on the basis of the hot pursuit doctrine because there was no immediate or continuous pursuit of the defendant from the scene of the crime. Also, his arrest cannot be justified on the basis of public safety because the defendant had already arrived home and had abandoned his car at the scene of the accident. Finally, the defendant’s warrantless arrest cannot be justified as an emergency simply because evidence of the defendant’s blood-alcohol level might have dissipated while the police obtained a warrant. Therefore, the defendant’s arrest was invalid.