The Supreme Court issued a ruling yesterday limiting the circumstances in which prisoners need to be read their rights prior to interrogation. The case hinged on an inmate who confessed to a sex crime after being questioned for five to seven hours by armed deputies without being read his Miranda rights. The prisoner, Randall Fields, was being held for disorderly conduct in a Michigan jail and was told he could return to his cell. In a 6-to-3 vote, the majority, led by Justice Samuel Alito, said Fields was not considered to be in custody at the time.