Not to rush the general election on primary day, but come Nov. 8, Missouri voters will be asked to approve a voter ID measure. The constitutionality of voter ID was cast in severe doubt by three federal courts during the past two weeks, so Missourians should be prepared to vote no and save the state some money. Amendment 6, as it will be titled on the November ballot in Missouri, would require voters starting next year to present a government-issued photo ID before casting ballots. Such measures in other states have failed federal court challenges. Amendment 6 would force Missouri to spend a lot of money defending a law that doesn’t deserve to be defended. It is the fruit of a decade-long effort by Republican lawmakers to make it harder for many Missourians to exercise their rights to vote. In 2009, then Secretary of State Robin Carnahan estimated the number at 240,000 and identified most of them as minorities, the disabled and elderly.