GPS used to be that way to give the military access to accurate positioning and provide lower accuracy to others. They can still do this selectively to whole areas of the world should they want to.
The US claim that since 2008 they've been launching GPS satellites without selective availability capabilities.
That means 27 of the current working GPS satellites are older ones which do have SA which could be switched back on at any time, and 12 are newer allegedly non-SA equipped satellites.
