(Reuters) -The U.S. Supreme Court on Monday declined to hear a challenge to Washington state's law banning "conversion therapy" on children aimed at changing sexual orientation or gender identity in a case brought by a Christian therapist who calls the 2018 measure an affront to free speech rights. The justices turned away plaintiff Brian Tingley's appeal of a lower court's decision to throw out the case, rejecting his claim that the state is unlawfully censoring the way he speaks to his therapy clients in violation of the U.S. Constitution's First Amendment right to freedom of speech. The state has said it is regulating professional conduct, not speech.