A federal judge Tuesday gave the green light to a parks-advocacy group’s lawsuit that aims to stop the construction of former President Barack Obama’s $500 million presidential center. The center, which has been delayed due to litigation, was intended to open in 2021. The center is slated to built on a Chicago park beside Lake Michigan, near low-income neighborhoods where Obama worked as a community organizer and the University of Chicago, where he was a law professor. The advocacy group, Protect Our Parks, is accusing the city of illegally transferring park land to a private entity, The Obama Foundation. The group said city officials manipulated the approval process to skirt long-standing laws designed to ensure residents have unobstructed access to lakeside parks. The judge concluded the group has standing to sue because it represents taxpayers with concerns that providing parkland in the public trust to the Obama center violates their due-process rights.