Law enforcement officials can also search a residence, person, or electronic device with the consent of the person or owner without a warrant. If an officer sees illegal activity or contraband in plain view, they can act without a warrant.Officers may make an arrest: • pursuant to a warrant. Most arrests are done without a warrant. If a police officer sees you rob a bank, he does not have a warrant when he arrests you. Arrest warrants allow police to detain you based on probable cause that you've committed a crime. 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. Ignoring a warrant in California has consequences, including a charge of 'Failure to Appear. What is an Arrest Warrant? In California, police officers can arrest a suspect for committing a crime with or without a warrant.