One of the best arguments for health-insurance reform is that our traditional employer-based system often locked people into jobs they wanted to leave but couldn’t because they feared they wouldn’t be able to get affordable coverage elsewhere.

This worry was pronounced for people with preexisting conditions, but it was not limited to them. Consider families with young children in which one parent would like to get out of the formal labor market for a while to take care of the kids. In the old system, the choices of such couples were constrained if only one of the two received employer-provided family coverage.

Or ponder the fate of a 64-year-old with a condition that leaves her in great pain. She has the savings to retire but can’t exercise this option until she is eligible for Medicare. Is it a good thing to force her to stay in her job? Is it bad to open her job to someone else?

By broadening access to health insurance, the Affordable Care Act (ACA) ends the tyranny of “job lock,” which is what the much-misrepresented Congressional Budget Office (CBO) study of the law released Tuesday shows. The new law increases both personal autonomy and market rationality by ending the distortions in behavior the old arrangements were creating.

But that’s not how the study has been interpreted, particularly by enemies of the law. Typical was a tweet from the National Republican Congressional Committee, declaring that “#ObamaCare is hurting the economy, will cost 2.5 millions [sic] jobs.”

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Glenn Kessler, The Post’s intrepid fact checker, replied firmly: “No, CBO did not say Obamacare will kill 2 million jobs.” What the report said, as the Wall Street Journal accurately summarized it, is that the law “will reduce the total number of hours Americans work by the equivalent of 2.3 million full-time jobs.”

Oh my God, say opponents of the ACA, here is the government encouraging sloth! That’s true only if you wish to take away the choices the law gives that 64-year-old or to those parents looking for more time to care for their children. Many on the right love family values until they are taken seriously enough to involve giving parents/workers more control over their lives.

And it’s sometimes an economic benefit when some share of the labor force reduces hours or stops working altogether. At a time of elevated unemployment, others will take their place. The CBO was careful to underscore — the CBO is always careful — that “if some people seek to work less, other applicants will be readily available to fill those positions and the overall effect on employment will be muted.”

The CBO did point to an inevitable problem in how the ACA’s subsidies for buying health insurance operate. As your income rises, your subsidy goes down and eventually disappears. This is, as the CBO notes, a kind of “tax.” The report says that if the “subsidies are phased out with rising income in order to limit their total costs, the phaseout effectively raises people’s marginal tax rates (the tax rates applying to their last dollar of income), thus discouraging work.”

But the answer to this is either to make the law’s subsidies more generous — which the ACA’s detractors would oppose because, as the CBO suggests, doing so would cost more than the current law — or to guarantee everyone health insurance, single-payer style, so there would be no “phaseout” and no “marginal tax rates.” I could go with this, but I doubt many of the ACA’s critics would.

The rest of the CBO report contained much good news for Obamacare: Insurance premiums under the law are 15 percent lower than originally forecast, “the slowdown in Medicare cost growth” is “broad and persistent” and enrollments will catch up over time to where they would have been absent Obamacare’s troubled rollout.

The reaction to the CBO study is an example of how willfully stupid — there’s no other word — the debate over Obamacare has become. Opponents don’t look to a painstaking analysis for enlightenment. They twist its findings and turn them into dishonest slogans. Too often, the media go along by highlighting the study’s political impact rather than focusing on what it actually says. My bet is that citizens are smarter than this. They will ignore the noise and judge Obamacare by how it works.

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