Elected officials throughout modern American history have sworn oaths to uphold constitutions and pledged allegiance to the flag without much controversy. But in a handful of recent cases, these routine practices have fallen victim to the same political divisions that have left the country deeply polarized. Disagreements over abortion rights, gun control and treatment of racial minorities are some of the issues that have caused several political leaders to say they can’t take an oath or recite the pledge. Some Republicans point to amendments enshrining abortion rights in state constitutions....