The Obama transformation was achieved by laws granting unparalleled discretionary power to the executive branch—but where the law gave no discretion Mr. Obama refused to abide by the law. Whether the law mandated action, such as income verification for ObamaCare, or inaction, such as immigration reform without congressional support, Mr. Obama willfully overrode the law. Stretching executive powers beyond their historic limits, he claimed the Federal Communications Commission had authority over the Internet and exerted Environmental Protection Agency control over power plants to reduce carbon emissions.

When Obama empowered himself to declare Congress in “recess” to make illegal appointments that the courts later ruled unconstitutional, he was undeterred. In an action that Lyndon Johnson or Richard Nixon would have never undertaken, Mr. Obama pushed Senate Democratic Leader Harry Reid to “nuke” the rights of minority Senators to filibuster judicial nominees and executive appointments by changing the long-standing 60-vote supermajority needed for cloture to a simple majority.

American democracy has historically relied on three basic constraints: a shared commitment to the primacy of the constitutional process over any political agenda, the general necessity to achieve bipartisan support to make significant policy changes, and the natural desire of leaders to be popular by delivering peace and prosperity. Mr. Obama has transformed America by refusing to accept these constraints. The lock-step support of the Democrats’ supermajority in the 111th Congress freed him from having to compromise as other presidents, including Reagan and Mr. Clinton, have had to do.