The city of Memphis is challenging Tennessee's voter ID law.
In a federal lawsuit, the city says the law requiring Tennessee voters to present state-issued photo IDs before they can cast a ballot is unconstitutional.
The city tried to convince a federal judge that photo IDs issued by the Memphis Public Library system could be used by voters as a form of ID.
But, two days before the primary election, a judge ruled the library IDs are not valid as voter IDs.