The young men accused of the attack face felony assault charges and on Monday, their preliminary hearing got underway.
It was a tense moment in San Francisco Superior Court. Several of the Yale students faced the defendants for the first time since the New Year's Eve beating more than a year ago that made headlines across the country.
Several Yale students flew across the country to testify in what's expected to be three days of a preliminary hearing.
At issue -- should Richard Aicardi and Brian Dwyer of San Francisco stand trial for felony assault and battery.
"This was a brutal, one-sided beat down of kids who weren't fighting back," said Yale students' attorney Whitney Leigh.
Yale's a capella group, the Baker's Dozen, came to San Francisco on their national tour 16 months ago and they were guests of honor at a New Year's Eve party.
Rich Aicardi wore a Santa hat and Hawaiian shirt that night. Witnesses told us he taunted the young men from Yale when they sang the Star Spangled Banner at midnight.
"Rich was behind me and he said these were a bunch of, that this is the gayest s**t he ever heard and what a bunch of fags," said witness Hunter Fairman on March 7, 2007.
Aicardi exchanged heated words with the Yale students, and no one disputes this point -- that he used his cell phone to call in reinforcements.
"He said, 'I'm 20 deep, my boys are coming,'" said party host Reno Rapagnani on January 8, 2007.
A nearby surveillance camera caught the van with Aicardi's friends at the scene.
The Yale students testified on Monday, as they left the party two or three at a time, they were attacked.
William Bailey said Rich Aicardi hit him in the jaw with a closed fist.
Evan Gogel testified one of Aicardi's friends tackled him to the ground, and a gang of eight to nine young men punched and kicked him. He suffered a concussion.
But, Baker's Dozen member Sharyar Aziz suffered the most serious injuries when a group attacked him.
"Besides any bruising or scrapes to the face, the main injury I suffered was I broke my jaw in two places," said Yale student Sharyar Aziz on January 8, 2007.
"The witnesses have accounts which vary greatly which demonstrates their level of intoxication," said Dwyer's defense attorney Tony Brass.
On Monday, defense attorneys for Aicardi and Dwyer highlighted the fact that the Yale students had also been drinking that night -- and they floated the idea of "mutual combat."
"You will find out one, the Star Spangled Banner had nothing to do with this and two, these Yale boys were not pure little angels here, in fact you will hear the cops say that they were, let me think, argumentative, uncooperative and intoxicated," said Aicardi's defense attorney Jim Collins.
"There very well might have been mutual name calling by the two sides and an argument, but whatever happened at the start of the night, by the time at least two victims, Mr. Aziz and Gogel, 19 year-old kids, were on the ground with people kicking them in the head, that's a very serious crime," said Yale students' lawyer Jim Hammer.
Late on Monday, Yale student Bryan Bibler testified he saw Rich Aicardi punch Sharyar Aziz, the young man who had his jaw broken in two places.
The prosecutor on the case is withholding comment, until this gets to trial, and that should be this fall, if all goes as expected.