What are examples of probable cause for a traffic stop or a vehicle search?

Gary Churak’s Answer

Well, the probable cause is very, very loose. Basically, the officer, all he needs to do is observe an irregularity while you’re driving. In San Antonio, that means anybody on the road after 12 o’clock is basically a DWI suspect. And if the officer finds any kind of driving infraction, even the smallest one like crossing a centerline without — crossing a line without signaling, he will pull you over and if he believes that you are — have been drinking, he will ask you if you’ve been drinking, if you say yes or no, he will come and provide the field sobriety test, the HGN, the walk and turn and the one-leg stand to determine if you were under the influence of alcohol. If he determines you are under the influence of alcohol or drugs, he will basically take you downtown. If it’s alcohol, he will offer you a breath test. If you refuse, in Bell County, he will get a warrant for your blood. If he believes you’re under the influence of any kind of drug, he will go directly to the blood draw and get a warrant for that.