FindLaw: U.S. Constitution: Fourth Amendment: Annotations pg. 2 of 6Much litigation has concerned the sufficiency of the complaint to establish probable cause. Mere conclusory assertions are not enough.
If you and I have some sort of altercation in traffic, and I call 911 and report you with a description and tell the dispatcher you are a drunk driver weaving all over the road, (because I want to see you get in trouble) they can dispatch an officer to investigate, but they cannot legally pull you over until they observe those actions themselves or find another viable reason to pull you over. They just can't go on what I told them as the gospel truth.