Sunday marked the 25th anniversary of the Americans with Disabilities Act, a federal law that prohibits discrimination against people with disabilities, and requires businesses and public services to make their facilities accessible to disabled individuals. At the time of its enactment in 1990, the legislation was a point of extraordinary consensus, which helped it clear Congress with overwhelming majorities, and a quarter century later, it remains one of the most politically bulletproof federal regulatory laws on the books. The occasion this weekend invited great fanfare, including from Republican House Speaker John Boehner (who became a representative only after ADA’s passage) and Jeb Bush (whose father signed the bill into law). But conservatives have generally greeted the anniversary with silence, and it's a fitting silence because it accounts for the critical ways American politics have changed in the intervening 25 years.

Given what we know about today’s Republican Party, it stands to reason that few or none of the GOP primary candidates this cycle would support ADA, and that ADA would fail in Congress, if it were introduced as new legislation today. Back in December 2012, one month after President Barack Obama’s re-election, 38 Republican senators aligned to defeat a U.N. treaty extending ADA-like requirements abroad, on the dubious grounds that it might impose stricter disability requirements on U.S. states. Republicans rejected the treaty in front of a wheelchair-bound Bob Dole, who attended the vote to demonstrate his support for ratification. 

In general, and whether it’s true or not, Republicans tend to oppose federal regulation on the grounds that regulation imposes heavy burdens on businesses. In 1990, opponents to the ADA, such as they were, made precisely this argument. And they weren’t wrong! Requiring places of business to accommodate disabled people is an obviously worthy undertaking, but it isn’t necessarily a cheap or easy thing to do.

It’s not that the burdensome-to-business objection is a red herring exactly, but the ADA shows that once upon a time not too long ago, Republicans in Congress were happy to override that objection if they viewed the underlying regulatory goals as particularly worthy. Either that’s no longer true, or Republicans have determined that every worthy federal regulatory goal has already been achieved, notwithstanding huge un- or under-addressed issues like climate change, LGBT discrimination, and financial market risks.

Because ADA is so deeply embedded in our culture, and addresses the needs of such a sympathetic class, it will probably never face a serious political threat. But other points of national consensus aren’t quite so strong, and in the same 25 years since ADA became law, we’ve seen those consensuses fray, and political threats to them mount.

If a Republican wins the presidency in 2016, he will enter office with robust congressional majorities, and the power to enact the consensus-shattering provisions of the Republican budget.

Bush, who’s probably the most consensus-oriented Republican in the 2016 race, told the audience at an Americans for Prosperity event in New Hampshire last week, “we need to figure out a way to phase out [Medicare] for [younger Americans] and move to a new system that allows them to have something, because they’re not going to have anything.”

When liberals note that the Republican Party wants to “end Medicare as we know it” and replace it with a system that provides seniors with vouchers to buy private insurance, Republicans get bent way out of shape, but when Republicans talk amongst themselves, they often acknowledge the truth with unexpected clarity and candor. This isn’t just true of Medicare privatization, but of similarly radical proposals to reform Social Security, Medicaid, to weaken anti-discrimination laws and so on.

In a hierarchy of federal protections, ADA probably rates the most politically successful, with Medicare and Social Security further down the list. But most of these protections are the products of a lost era in which Republican politics didn’t reactively foreclose the idea of using federal power in service of the common good. The change we’ve seen since is reflected everywhere, from Senator Rand Paul’s admission that he would not today support the public accommodation provision of the Civil Rights Act, to the Republican Congress’ ongoing reluctance to repair the nearly fatal damage the Supreme Court did to the Voting Rights Act, to its ongoing assault on the Affordable Care Act. It’s difficult to overstate the importance of the anomalous historical era that gave rise to most of these protections, because we've entered a period where more political effort is expended defending than expanding them. If we didn’t already have an ADA to celebrate this weekend, we probably wouldn’t be getting one anytime soon.