By Dan Diamond

The war over the Affordable Care Act may be over, but one battle shows no signs of waning.

The fight over Section 2713 of the Public Health Services Act under ACA’s Section 101 — better known as the health law’s regulation on preventive services — centers on contraception.

The benefit essentially calls for health plans to cover birth control and other services with no additional cost-sharing for enrollees.

But critics quickly seized on the administration’s initial proposal in 2011, which carved out an exception for “religious employers” — such as churches — but not for “religiously affiliated” employers — such as Catholic hospitals. As a result, HHS delayed implementation for religiously affiliated employers by a year but still required them to comply with the mandate.

In February, the White House released another accommodation for religiously affiliated employers. Yet rather than lay the issue to rest, the administration’s proposed amendments drew more than 400,000 comments — the most comments on any government regulation tracked by the Sunlight Foundation.

It’s just the latest salvo in an ongoing controversy. Opponents have filed more than 60 legal challenges against the benefit. Some have called it a “war on religion.”

While the sheer volume is astounding, there’s little mystery behind the root cause.

The contraception benefit touches on a half-dozen pressure points: Politics. Religion. Sex. Federal mandates. Federal entitlements.

“Our health care system is the dumping ground for all of our worst, unresolved arguments as a society,” J.D. Kleinke writes at The Health Care Blog. And the changes at the heart of Obamacare “spark every remaining culture war,” he adds.

And a mandate related to birth control is especially fraught.

“Anytime national policymakers mix health policy and social policy,” Joshua Archambault of the Pioneer Institute told me, “they should expect a strong reaction.”

Bishops Lead Charge Against Regulation

Under the proposal released in February, officials tried to clarify accommodations for religiously affiliated not-for-profits that object to offering contraceptive coverage — the employer’s insurer must provide the contraceptive coverage directly — and simplify which religious employers would be exempted from the rules. (You can read a quick summary here.)

Supporters of the law saw federal officials eager to compromise.

The White House “attempt[ed] to bend over backward to accommodate religious objections to contraceptive coverage in health insurance plans,” Elizabeth Sepper, a professor at Washington University in St. Louis, wrote in a Harvard law blog post earlier this year.

“I feel like the administration went the second and third mile trying to reconcile public health and gender equality with religious liberty,” Tim Jost, a law professor at Washington & Lee, concurred.

But the White House’s multiple iterations still haven’t settled all the difficult legal and philosophical questions around the regulation. Jost stressed to me that the administration hasn’t done very much to accommodate secular employers — opening up another front in the fight over the rule.

And some critics maintain that any contraception mandate is misguided.

“Instead of plunging deeper into this legal and cultural quagmire, the administration might consider starting over and trying to accomplish its goal in a way that honors our national consensus on religious liberty,” Francis Manion writes at Religion & Politics. Manion is senior counsel for the American Center for Law and Justice, which has filed seven cases challenging the mandate.

The most vocal critics of the mandate, the U.S. Conference of Catholic Bishops, issued a statement that the administration’s latest proposal “maintains its inaccurate distinction among religious ministries,” while raising the possibility that “ministries may yet be forced to fund and facilitate such morally illicit activities.”

“The bishops’ reaction to the administration’s generous proposal suggests they don’t want liberty from the mandate. They want to end it altogether,” Sepper added.

Familiar Lesson: Controversy Follows Federal Mandates

Still, why has this rule struck such a deep chord? And how does it fit with other efforts to oppose the health care law?

Most of the opponents of the contraception mandate “are involved because of sincere religious belief,” Jost notes. But “I think this whole controversy has been met with glee by opponents of the Affordable Care Act and to some extent been manipulated by them.”

Yet the fight over contraception stands apart. “To give an idea of just how motivated foes and champions of the contraceptive provision are, consider that second-most remarked upon [ACA] regulation got all of 4,600 comments,” Nancy Watzman blogged earlier this year at the Sunlight Foundation.

One telling takeaway: The contraception benefit isn’t so much new as it’s new to folks who didn’t realize that similar regulations have already been in place.

“The central mandate — that most employers have to cover preventative care for women — has been law for over a decade,” Nick Baumann wrote at Mother Jones last year. “This point has been completely lost in the current controversy.”

Looking Forward

HHS is expected to issue a final rule on the contraception benefit in the coming months. And many observers expect that after so many rounds of negotiations, the White House will essentially stand its ground and hew closely to its existing proposal.

But that final rule won’t be the final word.

Given split rulings in the lower courts, the provision’s assuredly bound for the Supreme Court — although the fate of the entire Affordable Care Act isn’t at stake, this time.

Just an especially controversial part of it.

“The Supreme Court generally decides issues in the narrowest way that answers the question on the table,” Judy Waxman of the National Women’s Law Center told the Huffington Post earlier this month. “It could mean they would make some more narrow decision about whether the religious accommodation works and which group should get it.”

And even if the court strikes down the contraception mandate, “it’s inconceivable that they would they then say that the ACA is unconstitutional,” Jost told me.

Dan Diamond (@ddiamond) is Managing Editor of the Daily Briefing, a CaliforniaHealthline columnist, and a Forbes contributor. An earlier version of this post appeared in California Healthline.