Fourth Amendment

The Fourth Amendment to the U.S. Constitution is the rulebook for what police can and cannot do when they want to search you, your home, your car, or your phone — or when they want to detain or arrest you. It says government searches and seizures must be reasonable, and it generally requires a warrant supported by probable cause. When officers cross those lines, the evidence they collect can be thrown out.

How the Fourth Amendment Works in California

The Fourth Amendment applies to California through the Fourteenth Amendment, and the California Constitution provides parallel protection in Article I, Section 13. After Proposition 8 in 1982, California courts apply federal Fourth Amendment standards in deciding suppression issues, but the underlying protections — and the body of California case law interpreting them — remain robust. Suppression motions are litigated under Penal Code § 1538.5.

A search or seizure under the Fourth Amendment generally requires a warrant supported by probable cause and signed by a neutral magistrate. The warrant must describe with particularity the place to be searched and the things to be seized. There are important exceptions: search incident to a lawful arrest, consent searches, the automobile exception, exigent circumstances, plain view, inventory searches, and certain border and probation searches. Each exception has its own limits, and California courts have developed nuanced rules for each.

Detentions are governed by a separate framework. Under Terry v. Ohio, an officer can briefly detain a person based on reasonable suspicion — less than probable cause but more than a hunch — that criminal activity is afoot. Traffic stops fall under this rule, and the duration and scope of the stop must remain tied to its original purpose under Rodriguez v. United States. Stretching a routine traffic stop into a fishing expedition for drugs or weapons, without independent reasonable suspicion, violates the Fourth Amendment and can lead to suppression of everything that follows.

Modern Fourth Amendment law in California also covers technology. Carpenter v. United States held that long-term cell site location information is protected. Riley v. California requires a warrant before searching the contents of a cell phone seized incident to arrest. People v. Macabeo and related California cases extend these protections in significant ways. Drone surveillance, license plate readers, GPS tracking, and digital data have all generated active California litigation, and the law continues to evolve.

Why the Fourth Amendment Matters to Your Defense

The Fourth Amendment is at the center of more California criminal defense litigation than any other constitutional provision. Drug, weapons, and DUI cases especially turn on whether the underlying stop, search, or arrest was lawful. A successful suppression motion can dismantle the prosecution’s case entirely. This is why experienced defense attorneys spend so much time examining body camera footage, dispatch logs, warrant affidavits, and consent forms.

Consent searches are a particularly fertile ground for challenge. Police often rely on consent that was given under pressure, in a language the person did not fully understand, or in a context where a reasonable person would not have felt free to refuse. California courts examine the totality of the circumstances under People v. Smith and related cases, and skillful defense work can frequently establish that the supposed consent was not truly voluntary.

Warrant litigation is another area where careful work pays off. Affidavits supporting warrants must lay out specific facts establishing probable cause, and Franks v. Delaware allows the defense to challenge warrants where the affidavit contains material false statements or omissions made knowingly or with reckless disregard. Successful Franks challenges can invalidate warrants and lead to suppression of all the evidence they produced. This is the kind of meticulous criminal defense work that separates routine representation from real advocacy.

Related Legal Terms

Fourth Amendment litigation drives the doctrines of probable cause, search warrants, the suppression motion, the exclusionary rule, and fruit of the poisonous tree, with carve-outs under the good faith exception. These concepts are central to our DUI defense, drug crimes defense, and weapons charges work across Greater Los Angeles.

Facing Charges Where This Applies?

If your case began with a stop, a search, an arrest, or a warrant, the Fourth Amendment is almost certainly part of your defense. Attorney Chris Nalchadjian offers free, confidential consultations 24/7. Call KN Law Firm at (888) 950-0011.