The Supreme Court isn't expected to rule until later this month on the constitutionality of the Affordable Care Act, but there's been some interesting developments as outside interest groups prepare for what they say might occur.

This week a few of the larger health insurance carriers - UnitedHealth, Aetna and Humana - announced that no matter how the Supreme Court rules on the health care law, they would allow some of the more popular insurance reforms to go forward. UnitedHealth, for instance, said it would allow young adults to stay on their parents' health plans, a popular provision of the law that is currently in effect.

"The protections we are voluntarily extending are good for people's health, promote broader access to quality care and contribute to helping control rising health care costs. These provisions make sense for the people we serve, and it is important to ensure they know these provisions will continue," said Stephen J. Hemsley, president and CEO of UnitedHealth Group, in a statement.

Read More About the Insurance Companies' Announcement

But today a public interest group supporting the health care law - Health Care for America Now - issued the following warning: "Don't be fooled by the Big Insurance Companies."

In the statement the group said that the insurance companies were going on a "PR offensive" and hoping to send a signal to the high court:

"The coordinated announcements by three of the five biggest health insurance companies is a cynical tactic to signal to the high court that it's okay to gut the law and remove its consumer protections because the health insurance companies will act responsibly and police themselves. No more insurance company abuses. The free market won't cost consumers their health anymore. The insurers' message to the court, it would seem, is that it's a new day so we can stick with the old rules."

And what Health Care for America now says what will really happen is this:

"What the insurance companies didn't say - and what they won't do - is the real story. They aren't saying they will stop discriminating against people with pre-existing conditions as the law requires beginning in 2014. That would be a big deal, because that part of the law will stop 129 million people with chronic conditions like diabetes, high blood pressure and asthma from being overcharged or being denied coverage. They also have not offered to keep covering children with pre-existing conditions - a provision which has already taken effect and insurers have fought.

"The insurers got publicity this week for appearing to make a positive gesture, but the changes they've announced are voluntary, meaning consumers and small businesses can only count on the policies to last as long as it's financially convenient for the insurers. But goodwill gestures aren't enforceable when you're sick. Insurance companies can't be trusted to behave as good actors unless laws are on the books to prevent them from being bad actors."