The law, which took effect last year, says people with felony convictions regain the right to vote after they have completed any prison term.

Quinn ruled the law was unconstitutional in a pair of orders in which he sentenced two offenders to probation, but warned them they were not eligible to vote or to register to vote — even though the law says they were. It was an unusual step because nobody involved in those cases ever asked him to rule on the constitutionality of the law.