If the officer had no legal reason to pull you over, that can undo the entire DUI case. Your attorney can file a motion to suppress every piece of evidence gathered after an unlawful stop, and when that evidence disappears, the prosecution often has nothing left.
One clarification on the terms. To pull you over, police need reasonable suspicion that a law was broken, like weaving, speeding, an expired registration, or a broken taillight. To arrest you, they need the higher standard of probable cause that you were driving under the influence. Both stages have to be lawful. If the stop was a hunch with no articulable reason, or the officer invented a violation that the dashcam contradicts, the stop can be challenged.
Here's why it matters so much. Your breath or blood result, the field sobriety tests, the officer's observations, all of it flows from the stop. Knock out the stop and everything downstream can be suppressed under Penal Code 1538.5. Judges take these motions seriously when the record backs them up.
This is exactly why the police report, dashcam, and bodycam footage get reviewed line by line. See how Joe approaches these fights on the criminal defense page.
This is general information, not legal advice, and every stop is different. To have your stop reviewed for free, call (858) 622-7280 or visit /contact.