The Food and Drug Administration, which oversees a vast swath of items people use every day, is expected to see an increase — perhaps an onslaught — of lawsuits following the Supreme Court’s decision on Friday.

“This is disastrous for public health. This is disastrous for the critical role of science-based regulatory agencies,” said Mitch Zeller, a former F.D.A. associate commissioner and tobacco division director. “Chevron has worked well for half a century and makes a lot of sense.”

Challenges could range from whether tainted spinach can be traced back to a farm to the very core of the F.D.A.’s decisions on whether drugs are safe and effective enough to be sold in the United States.

“F.D.A. has always been called the gold standard for product approval throughout the world,” said Perham Gorji, a partner at the law firm DLA Piper and former deputy chief counsel at the F.D.A. “Less deference to F.D.A. is going to obviously change what’s available in terms of products that are available here in the United States.”

The agency employs about 18,000 people, many of whom are doctors or have advanced degrees in biostatistics, chemistry and toxicology. Given the complexity of some scientific decisions the agency makes, attorneys who focus on the F.D.A. said initial challenges might focus on areas in which the F.D.A. exerts policy clout, including some that touch on drug pricing.

Chad Landmon, an attorney with Axinn who leads the F.D.A. practice group, predicted that early lawsuits could stem from a mix of problems companies face.

“I think companies are going to be much more aggressive and generally are going to be looking for opportunities to challenge the F.D.A.,” Mr. Landmon said.

Others expect a broad onslaught from tobacco companies regulated by the agency. “I would expect the tobacco industry to target every aspect of the F.D.A.’s regulatory infrastructure,” said Desmond Jensen of the Public Health Law Center. The agency decides which e-cigarettes are authorized for sale and can reject new cigarettes that could attract new smokers.

Limits on Chevron are widely thought to favor industry, but the reality could be more complex if advocacy groups gear up, said Nick Shipley, a former lobbyist for BIO and PhRMA and the founder of Cronus Consulting. He cited the group that challenged the F.D.A.’s approval of abortion medications.

“Industry,” he said, “could be caught in the crossfire.”