Mitchell Paulson claims Bach was driving under the influence when she slammed into his car and injured him.
Bach -- David Hasselhoff's ex -- pled no contest to the DUI -- which occurred in March -- and was placed on probation.
As we first reported Bach was arrested Saturday night for DUI, blowing a .13 and a .14. She will likely go to jail for the repeat offense. A law enforcement source tells TMZ Pamela was "hammered" behind the wheel.
As for the lawsuit ... Paulson is seeking unspecified damages.