Yes, as a defendant, you are entitled to review the discovery in the case provided by the prosecution. Your lawyer should not withhold it from you.
Court rules specifically require the prosecution to turn over material such as police reports, witness statements, the results of scientific tests, as well as any evidence that might show you did not commit the crime or that might mitigate in your favor at sentencing.
Other items that must be furnished include a list of the witnesses who will testify against you, including expert witnesses, any statements or confessions you gave to police and any concessions granted to witnesses who are testifying against you. In some cases, the prosecution has to disclose the identity of confidential informants.
You are also entitled to review any affidavits submitted for search warrants or wiretaps or other form of electronic surveillance.
Procedures vary from state to state, particularly as to the timing of the required disclosures.
Some discovery, such as grand jury testimony or statements of witnesses who may be cooperating against you, could be subject to a protective order preventing your attorney from providing you with your own copy of the discovery. In this case, if you are in custody, you would have to review the protected material with your attorney when he or she visits you. If on bond, you would have to review it at his or her office.
In addition to documentary disclosure, you have the right to view any physical evidence the state plans to introduce against you. This would have to be done at the prosecutor's office or police agency and likely will require an advance appointment.
If you have not reviewed the discovery in your case, ask your attorney to provide you with a copy. As you review it, takes notes so that at a later date you can point out to your counsel specific parts you believe to be inaccurate or of particular importance.
If your attorney is not willing to furnish you with a copy of the discovery, or allow you to review it at his or her office, ask for a written letter explaining the reasons. Also take a look at your fee agreement with your lawyer. If it provides that you are responsible for the cost of duplication, make sure that you have provided your counsel with the necessary funds.