A peace officer may make a valid arrest without a warrant in certain circumstances other than those set out in this instruction. The main difference between the two is that false arrest requires an arrest, but, false imprisonment only requires unlawful detention.If you are arrested without probable cause and falsely charged, can you sue the arresting officer? How would you go about doing this? The plaintiff's claim in a warrantless false arrest lawsuit arose from a sheriff s deputy s visit to her house to check on the welfare of her daughter. No warrant is required. Call (212) 587-8423. Page II of 13 - Plaintiff's Memorandum on Arrest Without Warrant. In the United States, it is a fundamental civil right that citizens cannot be detained or arrested without probable cause. Under this interpretation, a plaintiff would have a claim only if he can establish that his arrest (seizure) was unlawful.