There is a kid in our neighborhood that has assaulted my younger brother before. He keeps coming over and playing with other neighborhood kids including my brother. Today, he again pushed my brother down. Can my parents have him arrested for trespassing if he is on our property? If they can, how do they get the police involved?

If you are in immediate threat of physical harm, call 911.

According to Arizona Law (A.R.S. § 13-1502), it is criminal trespass in the third degree for someone to knowingly enter or remain unlawfully on any real property after a reasonable request by the owner to leave. Criminal trespass in the third degree is a class 3 misdemeanor. According to A.R.S. § 13-1504 a person commits criminal trespass in the first degree by knowingly entering and remaining unlawfully in or on a residential structure (class 6 felony) or entering or remaining unlawfully in a fenced residential yard (class 1 misdemeanor). However, to be convicted of criminal trespass, the trespasser must knowingly commit these acts.

See question #22310 which talks about the Arizona Bullying Law.

You may also want to report what is happening to your parents, to a guidance counselor at school or to a teacher.