Under PC 836, an officer can arrest you without a warrant if they have "reasonable cause" or "probable cause" to believe you committed a crime. If peace officers are not able to show probable cause, an arrest or search may be invalid, and the resulting evidence may be excluded.If they cannot develop probable cause, they will sometimes complete a field contact card for inclu- sion in a database or for referral to detectives. Yes, if an officer has probable cause to believe someone has committed a crime, they can arrest them without a search or arrest warrant'. The standard for initiating a contact is not "probable cause," "reasonable suspicion," or any other specific indication of criminal activity. Gavin Newsom's letter to Oakland city leaders last month urging them to change the city's policy on police vehicle chases seemed out of the ordinary. Probable cause is a Fourth Amendment requirement that usually must be met before the police make an arrest, conduct a search, or receive a warrant. The Oakland Police Department is committed to making information available to the public when requested. 4. What if I am arrested without probable cause? If the offense occurred more than 365 days prior1, there is no probable cause to arrest.