Metro council member Barbara Shanklin is suing Mayor Greg Fischer.
She is asking a judge to stop a pending city ethics commission investigation against her until the mayor's office gives her documents that it got last fall.
The suit claims Shanklin needs the paperwork as part of her defense against charges she and her family benefited from an upholstery program paid through her office.
The Metro Ethics Commission could issue sanctions against her next month.
Shanklin wants to know whether the mayor had the authority to shut down the upholstery program, once questions arose about it.