Yes, you must comply with the requests. And they must comply with your requests if properly propounded (timely, within the scope of the prosecution, not overly burdensome, etc.). If you intend to present evidence other than what you've provided as a response to a request for discovery, it can't be admitted. They're entitled to know what evidentiary material you have; likewise, you are entitled to theirs - it goes both ways. You could request a continuance, and request the same stuff from them. You're entitled to police reports, photographs, videos, radio transmissions, expert reports, police personnel records, expert names and subject matter they will testify on, any publications they intend to rely on; "any and all materials intended to be relied upon" and requst a copy thereof (which you will need to pay for). If you have an expert who will qualify to state with authority that that stretch of highway is a well known speed trap (or something of that nature); or an expert who has credentials to state that radar to calculate speed is flawed 50 percent of the time (whatever), then they're entitled to know who will be testifying. Without knowing what you intend to present as a defense, it's difficult to know what will be the most pertinent evidence.

