The challenge to Obamacare was, at its heart, a libertarian challenge, writes law professor Josh Blackman. The legal arguments were fashioned by prominent libertarians, such as Georgetown law professor Randy Barnett. The law being attacked was one libertarians opposed for decades on policy and economic grounds. And, the notion of mandated health insurance is inherently anti-libertarian. But, this was not only a philosophical argument, or one of policy, Blackman observes. As the Supreme Court's opinion demonstrated, these libertarian principles resonated strongly in the structural protections of our Constitution, which stood as bulwarks against two of Obamacare's biggest increases of federal power: the individual mandate and the Medicaid expansion.