Generally, police can question you after detaining or arresting you. However, you can insist on your right to remain silent. If the police have arrested you because you have committed an indictable offence (more severe offence like murder, rape, robbery, assault, and break and enter which are dealt with in District or Supreme Court), or they suspect you have, they must caution you about your right to remain silent.
Before questioning you, they must also tell you that any statements you make might be used as evidence against you.