When conservatives decry judicial activism, the target is inevitably a liberal judge whose rulings reach beyond interpreting law to making law. But misguided activist judges aren’t limited to the political left, as last week’s federal court ruling against the Affordable Care Act shows.

Ruling on a lawsuit brought by Texas Attorney General Ken Paxton and his counterparts in 19 other states, U.S. District Judge Reed O’Connor in Fort Worth concluded that the entire ACA is unconstitutional because Congress removed a key provision in the health care law.

This editorial board has had serious problems with the ACA from its inception. We’ve worried that while well-intentioned, it would be unaffordable. And we worried about its constitutionality before U.S. Supreme Court Chief Justice John Roberts bailed out the law in 2012, defining a key provision in the individual mandate as a tax. The “tax” — really an unconstitutional penalty — disappeared when Congress passed the 2017 tax cut bill, opening the door for O’Connor’s ruling.

If conservatives can fault the Supreme Court’s 5-4 decision in 2012 as rewriting the intent of Congress to describe a penalty provision in the individual mandate as a constitutionally permissible tax, they should be equally outraged by O’Connor’s rewrite of the rewrite.

In general, law builds from precedent and the impact rulings will have on existing practices. Faced with such decisions, courts, which don’t like to make policy, generally show restraint and default to the status quo.

Had O’Connor followed this path, he would have recognized that millions of people have come to depend on Obamacare for coverage. He also would have noticed that the GOP-controlled Congress’ repeal of the financial part of the individual mandate did not repeal the entire ACA. Therefore, O’Connor’s ruling is overreaching; its conclusion far wider and broader than Congress had authorized.

With a stroke of a pen, O’Connor now joins the ranks of federal judges who have gotten too far out over their skis. Legal experts predict the ruling most likely will be overturned on appeal. It should be.

Conservatives should be wary that O’Connor’s ruling also could emerge as a political albatross around the GOP. The Republican-controlled Congress had years to come up with a replacement for a health care law that they have called flawed. They did not.

FROM AN EDITORIAL IN THE DALLAS MORNING NEWS