GTA Vice City
It can be found in the locker room of the Washington Beach Police Station after comleting the mission Cop Land along with a Nightstick. While wearing the uniform, the player can explore the station without getting a wanted level. They can also enter the Fort Baxter Air Base without getting shot.
GTA San Andreas
The outfit is required after getting 100% relationship with Barbara Schternvart. Like Grand Theft Auto: Vice City, wearing the outfit allows the player to venture into police compounds and restricted interiors without attracting police attention.