Regardless, the election commission tends to give committees the benefit of the doubt on these kinds of questions, campaign finance lawyers said.
But that is unlikely because of the current make-up of the commission and the regulatory environment, campaign finance lawyers and watchdog groups said.
Interestingly, the legal changes directly wrought by the case have turned out to be quite subtle, according to campaign finance lawyers and political operatives.
His academic side and a gregarious disposition mask the degree of influence he has as one of the Democrats' most aggressive campaign finance lawyers.
There has also been a similar shortage of publicly financed lawyers, said Susan Hendricks, the deputy chief of the criminal division for the Legal Aid Society.
"This is a group of lawyers who aren't just structured-finance lawyers, but lawyers who provide a large set of services to the world's largest financial institutions, banks and investment banks," Mr. Portnoy said.
Even operating just under that dividing line, however, does not mean they are safe, because it is possible the I.R.S., in particular, could classify many of their issue ads as political too, Democratic and Republican campaign finance lawyers said.
The fund incorporated in the UK with a structure in November, several independent finance lawyers told Bloomberg, that operates like a tax haven by allowing overseas investors to avoid US taxes and regulations.
What is remarkable, campaign finance lawyers and political operatives say, is that the ads were produced and paid for by Democratic Party officials in Nebraska and Washington — with the senator's close involvement as their star.
"You don't need to hire a team of campaign-finance lawyers to figure out how to evade disclosure under the Board of Elections regulation," said Adam Skaggs, a senior counsel for the Democracy Program at the Brennan Center for Justice at New York University School of Law.
