California’s statewide teachers’ union sent a letter June 27 to the Chino Valley Unified School board criticizing its recent decision to allow only government flags on school property—and threatening to take legal action against the board if the policy is not reversed. The board voted 4–1 June 15 to allow only the California and U.S. flags on school property. The California Teachers Association—with more than 300,000 members—in partnership with local union Associated Chino Teachers alleges in the letter the decision violates teachers’ right to free speech under the First Amendment as well as a state employment law. The union also...