It's been two weeks since the Dean Levin filed a $200,000 lawsuit again Robert Blumenthal, the collector-turned-dealer who runs Robert Blumenthal Gallery on the Upper East Side. Mr. Levin, a process-based abstract artist once profiled in these pages, claimed that he had not been paid for the works from his solo show last May—there were 30, and the show sold out. Though it's not altogether so uncommon for a gallery—especially a smaller and newish one like Robert Blumenthal Gallery—to be slow to pay its artists, Mr. Levin had had enough, and to the litigation he went.