But that group is far less reliant on donations from corporations and other outside groups than the other three main associations of attorneys general: the Republican and Democratic Attorneys General Associations and the Conference of Western Attorneys General. Those groups regularly convene attorneys general at resort hotels for closed-door events with lobbyists, who make donations in exchange for greater access.

A $125,000 donation to the Republican Attorneys General Association, for example, gives a corporate representative the right to participate in a weekend retreat with the nation’s Republican attorneys general, as well as an opportunity to make special, private presentations to them. Democrats have a similar, although somewhat lower-priced, arrangement that grants big donors “a unique opportunity for focused conversation with specific A.G.s in a small setting.”

Image Richard W. Painter, a former White House lawyer, asked for new bar association rules. Credit... Katherine Taylor for The New York Times

The list of companies that participated this year in closed-door events sponsored by the Republican and Democratic Attorneys General Associations, according to documents obtained by The Times, includes some that are targets of investigations or regulatory reviews. Among them are Trinity Industries, the manufacturer of guardrails that have been blamed in a series of fatal car accidents, and Comcast, which is seeking the consent of state attorneys general for a merger with Time Warner Cable.

Richard W. Painter, a University of Minnesota law professor who served as the chief White House ethics lawyer during the Bush administration, said that these events should be considered fund-raisers, and that official business should not be discussed.

“We need some specific rules, and one of them should be that prosecutors, whether state officials or federal, whether elected or appointed, never discuss specific pending investigations or cases, or the possibility of bringing cases, at political fund-raisers,” said Mr. Painter, who is now a fellow at the Safra Center for Ethics at Harvard. This month, he submitted a formal request to the American Bar Association to revamp its model rules, which are used as a template by individual states, as they relate to attorneys general.

Investigations into specific practices identified in the articles by The Times have started in three states, with Missouri examining actions by Attorney General Chris Koster that benefited campaign contributors, and with officials in Florida and Rhode Island examining whether lawyers who made appeals to the attorneys general there in recent years violated state law by not registering as lobbyists.