Arthur Lange was driving home when a police officer began following him with the intent to conduct a traffic stop, after observing Mr. Lange playing his music loudly and honking his car horn. When the officer turned on his lights, Mr. Lange was all but turning into his garage. As Mr. Lange continued into his garage and began closing the garage door, the officer exited his vehicle, prevented the garage door from closing, and entered the garage to question him. Based on the ensuing interaction, Mr. Lange was charged with driving under the influence.

Upholding Mr. Lange’s conviction and the officer’s warrantless entry into his home, the California state courts ruled that when an officer tries to arrest someone for a misdemeanor offense—any misdemeanor offense—and that person enters a private home instead of yielding to the arrest, an officer may always pursue that person into the home, without pausing to obtain a warrant, to make the arrest. The court stated that the seriousness of the offense in question has “no significance,” and it required no particular showing of exigent circumstances. The Supreme Court agreed to hear the case to resolve lower-court disagreement over misdemeanor pursuits ending in warrantless home entries. CAC filed a friend-of-the-court brief in support of Mr. Lange.

Our brief focused on the principles that governed warrantless arrests under the common law at the Founding, a matter that the Supreme Court often considers when assessing whether a search is “reasonable” under the Fourth Amendment. First, our brief explained that Founding-era common law prohibited officers from entering homes without the owner’s permission to make warrantless arrests, except in defined circumstances based on specific exigencies. We showed that entering a home was allowed only when necessary to make an arrest for the most serious crimes or to suppress a violent breach of the peace for the benefit of public safety.

Second, our brief explained that while the scope of the Fourth Amendment’s protections is not always defined by the common law, it was appropriate to apply the common law’s safeguards here. Since the Founding, many protections that the common law once provided against warrantless arrests have been eroded. The development of professional police forces and investigative law enforcement has transformed the nature of policing, making armed officers a more pervasive presence than when the Fourth Amendment was ratified. Meanwhile, many of the legal requirements for warrantless arrests have diminished, giving those officers discretionary arrest power far beyond what the Framers could have conceived of. These changes, we argued, make it critical to maintain the safeguards afforded by the common law against warrantless home intrusions.

In June 2021, the Supreme Court held that the Fourth Amendment requires the presence of case-specific exigent circumstances in order for police officers to enter a home without a warrant to make an arrest. Attempting to complete a misdemeanor arrest, the Court explained, does not categorically qualify as an “exigent circumstance” that allows for a warrantless home entry. In the majority opinion for the Court, Justice Kagan cited CAC’s brief as she detailed the common law’s traditional safeguards against warrantless home intrusions and how that history supported the Court’s ruling.