President Barack Obama signed the Patient Protection and Affordable Care Act into law one year ago this past week. The measure had cleared the House two days earlier, and the Senate the previous Christmas Eve — at four in the morning, by one vote. Those three steps are usually enough to transform a bill into a permanent fixture of U.S. law. But this was no ordinary bill.

Before Obamacare cleared Congress, voters in Massachusetts elected a Republican to the U.S. Senate in the hope of stopping it. Thirty-eight states had introduced, and two states had enacted, legislation to block it. In the year since, six additional states have enacted laws, and two states have amended their constitutions to block it.

Twenty-eight states have sued in federal court alleging the law violates the Constitution. Individual citizens have filed another two-dozen challenges. Many of these lawsuits are frivolous, but not all are: Two federal courts have struck down all or part of the law as unconstitutional.

Opposition to the law contributed heavily to sweeping Republican gains in the 2010 elections. The House quickly voted to repeal it. Twenty-one governors have threatened not to implement it. At least four states have frozen, returned or refused the federal funds it offers. Three governors have refused to implement it.

Despite assurances that Americans would like the law once they found out what is in it, familiarity has bred contempt. Public opinion shifted against the law the moment the first draft appeared in Congress in June 2009, and a majority or plurality of the public has consistently opposed it ever since. Among likely voters, opposition leads support by nearly 20 points. A recent poll found seniors oppose the law by 12 points. Small businesses are among those suing (so far successfully) to overturn it.

This isn’t how it was supposed to happen. Universal coverage never provoked such a backlash in other countries, nor did Social Security, Medicare or Medicaid. What’s going on?

It’s not just partisanship. For one thing, 34 House Democrats voted against final passage, three voted for repeal, many are open to rescinding specific provisions, and even some Democratic pollsters have assailed the law.

Many Americans believe Obamacare claims a power Congress should not and does not have. A government that can make us purchase health insurance can make us buy cars or broccoli or cigarettes. The idea that Congress’ power to “regulate” commerce somehow includes the power to compel commerce does not sit well with the structure and purpose of the Constitution.

Others see it as a barrier to better, more-affordable health care. A similar law in Massachusetts led to rising costs, modest coverage gains, questionable health effects, longer waits to see a doctor and has opened the door to rationing.

Projections that Obamacare will permanently eliminate 800,000 jobs — not to mention any temporary job losses — strike fear in those battered by the recession.

Finally, many Americans are taking this law personally. The president promised he would “put an end to the game-playing,” but then made backroom deals with the drug lobby and Wal-Mart while Senate Democrats used tax dollars to buy votes. They watched Health and Human Services Secretary Kathleen Sebelius repeatedly censor insurers who disagreed with her. They hear Obama continue to say things they know are untrue, and that nonpartisan observers or his own advisers have discredited — like Obamacare will allow Americans to keep their coverage, reduce costs and reduce the deficit. First, the individual mandate was a tax, then it wasn’t, then it was. At a certain point, people start to feel insulted.

Newt Gingrich predicts Congress will repeal Obamacare in 2013. Agree or not, you have to be struck by how plausible his prediction is.