California is once again fighting in federal court for a Jewish family’s right to have a precious Impressionist painting returned to them by a Spanish museum nearly 90 years after it was looted by the Nazis. The state is also defending its own authority to legally require art and other stolen treasures to be returned to other victims with ties to the state, even in disputes that stretch far beyond its borders. The state has repeatedly weighed in on the case since the Cassirer family first filed it while living in San Diego in 2005. Last year, it passed a...