WASHINGTON (AP) _ Supreme Court officials say they’re looking into a complaint by a teacher who says she and her students were prevented from praying outside the court building in Washington.

Alliance Defense Fund Senior Counsel Nate Kellum says the small group from a Christian school in Arizona had bowed their heads and begun praying for the justices when police stopped them.

Supreme Court spokeswoman Patricia Estrada says federal law allows traditional tourist activity on the court’s grounds, but prohibits standing in an “assemblage” that could attract onlookers.

Kellum says that appears to mean people can talk among themselves, but not to God. In a letter to court officials, the ADF threatens to sue unless quiet prayers are allowed in the future.

Estrada says the Marshal of the Court will “look into the events as described in the letter.”