What happens if you get arrested but the cop that arrests you never reads you your rights?

Contrary to what most people believe, a person is placed under arrest does not automatically have to be read the Miranda warning (i.e. "their rights"). This is a myth. The warning must only be given if a person is in custody and then questioned. However, once a person is in custody and questioned without being "Mirandized", any statements so made cannot be used against them (although the arrest may still stand).

There are 2 exceptions to the above: the statements were voluntarily and knowingly made anyway (that is the defendant waived his rights); or the questioning was incidental to the booking process (i.e. name, address, etc).

Note: Any questioning done before being taken into custody is legal.