The Supreme Court upheld Indiana’s voter-identification law on Monday, declaring that a requirement to produce photo identification is not unconstitutional and that the state has a “valid interest” in improving election procedures as well as deterring fraud. In a 6-to-3 ruling in one of the most awaited election-law cases in years, the court rejected arguments that Indiana’s law imposes unjustified burdens on people who are old, poor or members of minority groups and less likely to have driver’s licenses or other acceptable forms of identification. Because Indiana’s law is considered the strictest in the country, similar laws in the other...