Mr. Finney and another prominent Braun supporter, John W. Rogers Jr., head of Ariel Investments, had contributed $5,000 each to Carol for Chicago on Jan. 19. Mr. Rogers gave another $5,000 to United Communities of Chicago on Feb. 8, and Mr. Finney donated a total of $8,500 to the group before the election.

While neither the Braun campaign nor United Communities of Chicago has reported the expenditure to the state, United Communities of Chicago paid for a radio ad on behalf of the campaign last month. The spot featured Representative Danny K. Davis, Democrat of Chicago, urging blacks to vote for Ms. Braun, who had been chosen by Mr. Davis and other black leaders as the “consensus” black candidate. When he was a child, Mr. Davis said in the ad, “my father would tell us that the Bible says any man who will not support his own house is worse than an infidel.”

Mr. Higginbottom and Mr. Finney did not return calls seeking comment. Mr. Rogers said Friday that he had donated to United Communities of Chicago at Mr. Finney’s urging, because the group helped not only Ms. Braun but also black candidates for the City Council.

“There is a great need in our community, and so few pockets,” Mr. Rogers said. “I was just trying to be supportive of all of the candidates that they were helping.”

Another situation that arose in the mayoral race involved 10 people affiliated with the Jimmy John’s restaurant chain, each of whom contributed $5,000 to Rahm Emanuel’s campaign less than two weeks before Mr. Emanuel won the election. When Crain’s Chicago Business asked Mr. Emanuel’s aides about those donations, a spokesman for the campaign said the $50,000 from those donors had been returned “out of an abundance of caution and to avoid even the suggestion of impropriety.”

As with the checks from the Puigs and the Braun donors, however, there appeared to be no violation of the new law, provided that the Jimmy John’s employees made the donations out of their own pockets. Ms. Canary said she saw no breach of the rules unless the employees had been forced to make the contributions as a condition of continued employment or the company had reimbursed them for the donations.

State officials have not yet determined exactly how the new statute will work in practice, said Rupert Borgsmiller, the executive director of the Illinois State Board of Elections.