So the question essentially boils down to whether the payments from wealthy Edwards supporter Bunny Mellon to the candidate's mistress were meant to help his campaign or whether they would have been made regardless of whether he was running for president.
Federal prosecutors at the Justice Department are relying on an advisory opinion issued in 2000 by the Federal Election Commission which found that campaign regulations apply to an individual giving a gift to an candidate running for office. The FEC concluded that the "proposed gift would not be made but for the recipient's status as a Federal candidate; it is, therefore, linked to the Federal election," and was therefore subject to regulation.
But the Edwards legal team could bring up a 2002 opinion from the FEC which has some relevance to the Edwards case.
The issue at hand in that opinion was a $25,000 loan from drug company lobbyist Terry Lierman to Rep. Jim Moran (D-VA), who needed money to help pay off legal fees related to his divorce. Lierman's check was endorsed over to a law firm to pay for Moran's attorney.
"The FEC found that this personal loan was not a campaign contribution primarily because they determined that, given the pre-existing relationship between the donor and the candidate, the loan would have been given irrespective of the fact that Rep. Moran was a candidate for re-election at the time the loan was made," Brett Kappel, who worked on the case for Moran, told TPM. "The Edwards can make a similar argument about the Baron and Mellon contributions."
Other legal experts agree that federal prosecutors have a high bar to overcome.
"The problem with this theory is that it is not clear that these expenses fit the legal definition of a 'contribution'," Rick Hasen wrote for Slate. "As the indictment explains, that definition includes 'anything of value provided for the purpose of influencing the presidential election,' including contributions to a candidate. But it does not include payments for the personal expenses of a candidate if 'they would have been made irrespective of the candidacy.'"
Edwards' legal team has lined up experts like former FEC Chairman Scott Thomas to argue that the payments weren't donations to the presidential campaign. Thomas said in a statement that in his view the payments "would not be considered to be either campaign contributions or campaign expenditures within the meaning of the campaign finance laws."