Sofia Richie Has a Rough and Tumble, and Illegal Night Out

Sofia Richie made a scene at Catch Saturday night, with a little scuffle and a little scofflaw-ing.

Sofia's showed up with a dude, who got handsy with a photog.

On their way out, Sofia and crew poured into a waiting SUV ... problem is, there were too many passengers and not enough seatbelts ... a violation of CA law.

18 year olds ... they don't always make the best decisions.