Mr. Scalia also represented Walmart in a fight against a Maryland law that would have required it to spend more on health care and Boeing in a case involving a union that accused it of violating labor law.

He helped represent a coalition of financial services industry groups that sued to block an Obama administration rule requiring brokers to act in their clients’ best interest when advising them on retirement accounts.

During his Senate confirmation hearing this month, Mr. Scalia acknowledged his long track record representing corporations but argued that he was working diligently on behalf of his clients rather than to advance his own views. He said he was capable of working just as hard on behalf of American workers, citing the issue of ergonomics, on which he said he worked closely with the Labor Department’s career staff during his tenure there.

“The lawyer who had the lead on the issue of ergonomics wrote a letter, joined a letter from former career officials supporting my nomination,” Mr. Scalia said.

In the letter, 13 former Labor Department officials wrote that Mr. Scalia “was very supportive of enforcement litigation to vindicate the rights of workers.”

Democrats also questioned Mr. Scalia at his confirmation hearing over his views on gay rights, citing a college newspaper column in which he wrote that parenting by a lesbian couple should not be treated “as equally acceptable or desirable as the traditional family life.”

Mr. Scalia implied that his views on the subject had changed in the nearly 35 years since he wrote the column. “I would not write those words today, in part because I now have friends and colleagues to whom they would cause pain,” he said.