WASHINGTON: A US judge Monday ruled that a key provision in the Obama administration's landmark health care reform requiring all Americans to have insurance was unconstitutional. It was the first major legal blow to President Barack Obama concerning the radical overhaul of the nation's health care system which he has made a cornerstone of his administration. “On careful review, this court must conclude that Section 1501 of the Patient Protection and Affordable Care Act – specifically the Minimum Essential Coverage Provision – exceeds the constitutional boundaries of congressional power,” the federal judge said in his ruling. Experts say that the fate of health care bill – aimed at ensuring that some millions Americans who lack insurance are covered – will likely be eventually determined by the Supreme Court. The bill was signed into law in March. But various US states have vowed to fight the law, which only passed after months of bitter wrangling in Congress, and have mounted legal challenges against it with about 20 suits currently before the courts. – Agence France