School officials violated the law when they strip searched 13-year-old Savana Redding who they believed to be in possession of prescription-strength Ibuprofen, the court ruled Thursday.
The high court ruled 8-1, with Justice Clarence Thomas the lone dissenter.
Redding was attending Safford Middle School in Arizona when school authorities demanded she remove her clothes and shake out her underwear to see if she was carrying any pills after a fellow student accused her of giving her medication.
The school's vice principal searched Redding's backpack in his office but found nothing.
The 8th grader was then sent to the nurses office where she was told to take off her shirt and pants. Redding said school officials then demanded that she move her bra to the side and stretch her underwear waistband. No pills were found.
Officials cannot be held personally liable in a suit for the search, the court ruled. The lower courts will have to determine if the school district can be sued.
The suit was dismissed by a federal magistrate in April and appeals panel agreed the search was constitutional.
Last July, a full panel of the 9th U.S. Circuit Court of Appeals said the search was "an invasion of constitutional rights" and that the vice principal could be found liable.