COLUMBIA — A transgender student in Berkeley County can continue using the bathroom of his choice while a lawsuit continues, the nation’s highest court said Wednesday. The ninth grader, identified in court filings as John Doe, is suing the state over a budget clause requiring transgender students use the bathrooms and locker rooms that match their biological sex at birth. Last month, the 4th Circuit Court of Appeals said that student could use the school bathroom of his choice while the case proceeded, overturning a lower court’s decision. Attorney General Alan Wilson’s office asked the Supreme Court to overturn that decision, arguing the appeals court got it wrong. The budget clause, first added to the state budget last year, remained in the spending plan that took effect July 1.