The pair insisted they were only showing public affection, after police responded to a radio call from a concerned citizen about "indecent exposure" inside a silver Mercedes with the door open.
"As I was sitting in the back of the police car, I remembered the countless times my father came home frustrated or humiliated by the cops when he had done nothing wrong," Watts wrote on Facebook at the time.
Police said after the incident that "upon further investigation it was determined that no crime had been committed," while an audio tape recorded by the officer involved appeared to refute Watts' claim of racial profiling.
But following the emergence of various videos and photos, published notably by the TMZ celebrity news website, they apparently decided to investigate further and bring charges against the couple.
-AAP