Stunning. There’s just no other way to say it. John Roberts, the fifth liberal? Actually, the decision gets a little more complicated than that in its details, but the bottom line is the bottom line: the Supreme Court upheld the individual mandate—upheld the law pretty much in full. Several legal experts predicted this, but virtually no one in the political world thought it—everyone was braced for the opposite. Thousands of people in politics spent weeks readying themselves for a strike-down, and now suddenly, all the people have to turn on a dime and say, “Now what?”

President Obama gets a major vindication. I didn’t agree with liberals who’ve been writing for the past couple of weeks that an overturning of the mandate would constitute a tolerable split decision. On the substance, sure: the mandate is merely a means to an end, and there are other means that could be substituted for it. But on the politics? No. A mandate strike-down would’ve been horrible for Obama.

Part of readying myself for the opposite result included wondering how many times I could go without shooting the television as I watched Mitt Romney say words to this effect: “So now we know. The president, at a time when the economy was in the toilet, when unemployment was rising over 10 percent, devoted all his energy and all his political capital to a cause that we now know was a complete and total waste of the American people’s time.” Never mind the hypocrisy involved in the man who is the original political father of the mandate saying those words. It would have been a powerful argument to swing voters, and it would have hit Obama hard.

Now, he floats above it. There’ll be new polling soon, and it’s not as if the mandate is suddenly going to be popular because of the decision. Indeed, now that it’s a tax, it might be less popular! But on the simplest level this is a massive win for Obama, and no spin can undo that.

What does Romney do? In his statement shortly before noon, he announced that he was going to continue to fight to repeal the law. But there’s no getting around this: a huge hammer has just been swiped from his, as it were, mitts. “Repeal Obamacare” is still going to play well with the right-wing base, but to centrist voters, it’s going to sound increasingly churlish and loony. “C’mon,” they’ll think, “the Supreme Court settled this. John Roberts voted with Obama, for goodness’ sake.”

In other words, Romney’s own hypothetical argument, the one I mentioned above, can in essence be turned against him, and against all Republicans. “Repeal Obamacare!” Oh yeah? Who’s wasting the people’s time now, Republicans? You! This is settled law. There ain’t no place to go after the Supreme Court. It’s done. Until the Republicans have either (a) a House majority, 60 senators, and a president, or (b) 290 House members (that is to say, two thirds, or a large enough majority to override a veto) and 67 senators, then they’re in dreamland. Repeal of any aspect of it isn’t going to happen.

But what stops a bull in a china shop? Eric Cantor already said the House is going to vote on full repeal in July. You go, Republicans. I pray they spend their convention and every day of the fall campaign fulminating against health care. Without question, it’ll rally their base and might make some arch conservatives and libertarians back Romney who wouldn’t have. But they’re going to lose independents because they’re going to look like obsessed fools. Which, uh, come to think of it…

The Republican line now, I’d expect, will be: OK, if it’s not a mandate and it’s a tax, then Obama and Democrats just dramatically increased your taxes. That could be potent. It’s not an insubstantial amount of money, this penalty: for a $50,000 a year household, it’s $1,250. The Republicans are going to try to make it sound as if everyone in America is going to have to pay this tax, but, as is par for the course with Republican rhetoric, it has precious little intercourse with the reality of the situation. This “tax” will be paid only by a very small number of Americans (2 to 5 percent), since 85 percent of us have health care to begin with.

The Democrats will have to answer that. But the Democrats do have one pretty good answer: “John Roberts is on our side on this one.” I don’t want to go overboard in lauding Roberts. He’ll be rendering very conservative opinions for years to come. But he does appear here to have made a legal rather than a political decision, so he deserves credit for that.

This fight is a long way from over. But the dynamics of it sure have changed. The presumption of this debate is totally and utterly reversed. The law is validated. It’s not even the same law it was 24 hours ago. Now it has teeth, and standing, and the presumption that America should give it a chance to work. Its authors have those things now, too, and its opponents have nothing, except for more mud and more lies and more bitterness to inject into our politics. Glad to have lived to see a day when that actually didn’t work.