The justices ruled that Tennessee’s law, which prohibited some medical treatments for transgender youths, did not violate equal protection principles.

The conservative Supreme Court dealt a significant blow to transgender Americans on Wednesday, issuing a sweeping decision that may have implications beyond the medical care that was at center of one of the court’s highest-profile disputes this year.

The court’s decision allows the law in Tennessee and has implications for the 23 other states that have banned similar treatments in recent years.