Probable Cause

Probable cause is the level of proof police and prosecutors need before they can arrest you, search your property, or formally charge you with a crime. It does not require absolute certainty — just enough facts and reasonable inferences to make a cautious person believe a crime probably happened and you were probably involved. It is the legal line between a hunch and an arrest.

How Probable Cause Works in California

Probable cause comes from the Fourth Amendment to the U.S. Constitution and Article I, Section 13 of the California Constitution, both of which protect against unreasonable searches and seizures. California courts have repeatedly held that probable cause is a flexible, common-sense standard — more than reasonable suspicion (which justifies a brief detention) but less than the proof beyond a reasonable doubt required for conviction. Penal Code § 836 codifies the rule that an officer may arrest without a warrant when they have probable cause to believe a person has committed a felony.

The probable cause standard appears at multiple stages of a California criminal case. It is needed for an arrest, for a search warrant under Penal Code § 1525, for a magistrate’s holding order at a preliminary hearing under Penal Code § 872, and for a grand jury to issue an indictment. Each of these stages is its own opportunity to challenge whether the standard was actually met. A finding of probable cause at one stage does not necessarily protect the case if the underlying facts were misstated, exaggerated, or omitted.

When police seek a California search warrant, the affidavit submitted to the magistrate must lay out specific facts — not conclusions — establishing probable cause. Under People v. Camarella and a long line of California cases, defense attorneys can challenge warrants under Franks v. Delaware by showing that an officer made false statements or material omissions intentionally or with reckless disregard for the truth. If the falsehoods are essential to probable cause, the warrant can be invalidated and the evidence suppressed.

In warrantless cases — traffic stops, street encounters, in-home arrests — the analysis is even more fact-intensive. California courts examine the totality of the circumstances: what the officer saw, smelled, heard, and knew at the moment of action. Hunches, profiles, and hindsight do not count. If an officer arrests or searches without true probable cause, every piece of evidence flowing from that act can become subject to suppression under the exclusionary rule.

Why Probable Cause Matters to Your Defense

Probable cause is one of the most important battlegrounds in California criminal defense because it controls what evidence can be used against you. A judge who finds probable cause was lacking can suppress drugs, guns, statements, identifications, and digital evidence — and once that evidence is gone, many cases collapse. This is the heart of a Penal Code § 1538.5 motion to suppress, which is filed in countless DUI, drug, weapons, and search-and-seizure cases every year in California.

The same standard governs whether a felony case can move forward at all. At the preliminary hearing, the judge decides whether the prosecution has shown probable cause to “hold the defendant to answer.” A skilled defense attorney can use this hearing not just to challenge sufficiency, but to lock witnesses into testimony that becomes powerful impeachment material later. When probable cause is genuinely weak, charges can be dismissed before trial, and the case never gets in front of a jury.

Probable cause challenges also drive negotiations. When the defense identifies real Fourth Amendment problems — a questionable stop, a search that exceeded its scope, an affidavit with material omissions — prosecutors often respond with reduced charges, dismissed enhancements, or favorable plea offers rather than risk an evidentiary loss. Strong constitutional litigation is one of the most effective tools in modern California criminal defense, and probable cause is almost always at its center.

Related Legal Terms

Probable cause sits at the intersection of the Fourth Amendment, search warrants, unlawful search and seizure, and the suppression motion process. It also connects to the doctrines of fruit of the poisonous tree, the good faith exception, and the exclusionary rule — concepts that drive litigation in our DUI defense, drug crimes defense, and weapons charges practice.

Facing Charges Where This Applies?

If you believe police searched, arrested, or charged you without solid grounds, those issues need to be raised early and aggressively. Attorney Chris Nalchadjian offers free, confidential consultations 24/7 and routinely litigates probable cause issues across Los Angeles County. Call KN Law Firm at (888) 950-0011.