Venezuela's most famous political prisoner is one step closer to freedom, after the country's Supreme Court of Justice granted house arrest to Leopoldo López. The court called it "a humanitarian measure," citing the opposition leader's health.López, 46, has been serving a nearly 14-year prison term. The surprise move took effect Friday, the court said in a tweet Saturday morning.In addition to health concerns, the court's president, Maikel Moreno, mentioned "serious indications of irregularities" in the case.Moreno is one of eight justices on the high court who were hit by U.S. sanctions in May, in retaliation for the court's move to dissolve the National Assembly and take over legislative duties. The court is dominated by backers of embattled President Nicolas Maduro.Maduro was narrowly elected to succeed the late leader Hugo Chavez in 2013. The opposition won a landslide victory in legislative elections that were held in late 2015. Venezuela is slated to hold a new vote in late July, to form a constitutional assembly.Lopez's case has been disputed since 2014. As NPR reported in 2015: