The most controversial parts of the federal health law do not go into effect until 2014, but many provisions are already in place: Insurance companies now must cover young adults under their parents' plans until age 26; they cannot deny coverage to kids for pre-existing conditions or impose lifetime limits on coverage; and they must offer some preventive services such as mammograms and colonoscopies without co-pays.

If the Supreme Court strikes down the entire Affordable Care Act when it releases a decision this summer, experts say those offerings would no longer be mandatory.

"Presumably, if the whole law is struck down, those all go the minute the ruling is issued," said Robert Field, a health policy expert at Drexel University. He said it is unknown how insurance companies would react.

"Would they actually start throwing people off, would it be an orderly process, or would many of them decide, we're going to keep covering you anyway because we're now used to it and it seems like the fair thing to do?" Field said.

U.S. Sen. Pat Toomey of Pennsylvania says reversing some consumer mandates already in effect will allow free market forces to dictate what should -- and should not – be included in insurance plans.

"It's like with automobiles, they put AM and FM radio stations (in them) and then, when they could, they put GPS in them," Toomey said. "It's because people value them, people wanted them, and people were willing to pay for those things.

"I think that's a much better way to move than to have the government dictate what should be in a car and what shouldn't," Toomey said.

According to the federal government, almost 65,000 young adults in Pennsylvania gained insurance through a parent's coverage because of the health-law changes.

In Pennsylvania, insurance companies are typically not allowed to change coverage until the new plan years begin.

A Supreme Court decision is expected sometime this summer.