A North Carolina program of monitoring sex offenders by GPS needs closer judicial scrutiny, the Supreme Court ruled Monday, reports McClatchy DC.

In an unsigned and unanimous decision that could rattle a number of states, the court rejected North Carolina's arguments and concluded the ankle-bracelet monitoring program amounts to a search. The decision means convicted felons like Torrey Dale Grady can now challenge the life-long monitoring.

"That conclusion, however, does not decide the ultimate question of the program's constitutionality," the court stated, noting that "the Fourth Amendment prohibits only unreasonable searches."

North Carolina judges must now re-examine the GPS monitoring program through a Fourth Amendment lens that's adapting to new technologies. Whether it's permitted, the high court explained Monday, depends on "the nature and purpose of the search and the extent to which the search intrudes upon reasonable privacy expectations."