"...with no candidate taking a majority of electoral votes, the choice was instead thrust to Congress, where seven of twelve House delegations were needed to break the impasse. It was thought that Breckinridge was advantaged here, but he won only the six delegations of the six states he won. Harris won the five delegations of states he had won and also North Carolina's, where the anti-Vance House members threw their lot in with Harris, deadlocking the House of Representatives [1]. It was thought that this was done in a ploy for patronage. RMT Butler of the Senate, meanwhile, stated that his chamber would make no election of the Vice President until the Representatives had made their choice, viewed as an effort to appear neutral, though later claims emerged that this due to disagreements within the planter class on how to succeed and that Senator Sparrow had begun a campaign to bribe his colleagues into electing him.
Breckinridge addressed the gathered House on December 7, 1873, trying to convince them to give him a unanimous vote - to "continue the legacy of our dear President Forrest" and suggesting that only by acknowledging that he had the most electoral and popular votes, and thus was "the people's choice." Harris eschewed addressing the House, rather taking the battle for the Gray House elsewhere - the Supreme Court, where he filed suit against the President and claimed that the electors pledged to Breckinridge were in fact invalid, as a President was constitutionally ineligible to succeed himself at the expiry of a term. Breckinridge appeared before the Supreme Court's seven justices, four of whom had been appointed by his predecessor and one by him, to argue his case that he was eligible for "a term of own right," and that he was merely serving out Forrest's term as he had not received Presidential electors of his own ever before.
In one of the most surprising episodes in Confederate political history, and what became derided for decades as "the Crime of '73," the justices backed Harris's claim in an unsigned opinion, though Justice Alexander Stephens, the former Vice President [2] who had been appointed to the Court by Forrest, later claimed that the vote was 4-3 and that it had been Justice Joseph E. Brown who was the swing vote in Harris's favor (Stephens, who only served six years on the Court before returning to the Senate until his death, would never reveal how he himself voted, though he was generally thought to prefer Breckinridge). Harris v. Breckinridge set the precedent that a Vice President who assumed office on the death or resignation of his predecessor was ineligible to run for a term in his own right and set the precedent of the Supreme Court weighing in on elections, as they threw out all of Breckinridge's electors and granted all of them to Harris instead, as he had come in second place in every state he had lost. The result thus went from inconclusive to a landslide victory for the Harris/Early ticket, though rather than settle the matter the Court had poured fire on the political dispute and only inflamed opinions around the Confederacy..."
- Electoral History of the Confederate States
[1] Why you don't want an even number of states, I suppose
[2] because why not