The statute governing illegal receipt of campaign contributions "means any gift, subscription, loan, advance, or deposit of money... for the purpose of influencing any election for federal office."
The words "the purpose" suggests that in order for a conviction, the sole reason for the money would have to be to finance a presidential campaign.
Edwards' legal team has argued he did not know it might be illegal, did not intend to break the law and that his main reason for hiding Hunter was to keep her secret from his wife, Elizabeth, who was dying of breast cancer.
Prosecutors, however, are arguing the law should be interpreted to mean "a purpose," meaning use of the donations does not have to be solely for a political campaign.
"It is sufficient under the law if you find that the gift, purchase, or payment was made for, among other purposes, the purpose of influencing any election for federal office," prosecutors argued in court filings last week.
Edwards' lawyer Abbe Lowell has argued that prosecutors are asking the jury to "invent a new crime" with its interpretation of the law.
The defense is also expected to go after the prosecution's key witness Andrew Young, a former Edwards' aide who helped hide Hunter, going on the road with her to keep her away from the press, even claiming paternity for his boss.
Edwards defense has argued that much of the money was solicited by Young and he used the scandal to enrich himself.
Among Edwards' witnesses will likely be his daughter Cate, who has been his most visible supporter throughout the trial.
Hunter is on Edwards' list of witnesses, but it's not clear whether she will be called. Her presence in the courtroom could be volatile.
It's not yet known whether Edwards will take the stand in his own defense.