Boyd pleaded guilty to rough conduct but challenged the impact grading, arguing a head clash between teammate Adam Cerra and Byrne-Jones immediately prior to the tackle contributed to his concussion.
Carlton called a doctor who said it was impossible to determine which impact had caused Byrne-Jones' concussion, the club arguing Boyd shouldn't be excessively punished for a tackle that might not have caused any actual injury.
But tribunal chairwoman Renee Enbom and her jury were satisfied on the balance of probabilities the tackle did affect the concussion, noting "far less impact" on the Cerra clash compared with his head hitting the ground after the tackle.
They found the impact was severe due to Byrne-Jones' unbroken fall combined with excessive force in the slinging motion.
Boyd will miss Carlton's games against West Coast, Collingwood and St Kilda.
Later, Sydney co-captain Dane Rampe will front the tribunal to challenge the two-match ban he was dealt for rough conduct over a collision with Western Bulldogs midfielder Lachlan McNeil.
McNeil was clearly hurt in the off-the-ball incident that occurred during the Swans' nailbiting win last Thursday night, but played out the match.
On Monday, the Bulldogs confirmed the 22-year-old had experienced delayed concussion.
"He completed the game without any obvious concerns, but then post-game reported that he started to suffer from some subtle signs that can be related to concussion," Bulldogs head of sports medicine Chris Bell said.
"After clinical assessment, the doctors confirmed that McNeil had suffered some delayed signs of concussion."
Swans coach John Longmire defended Rampe, claiming the experienced backman was focused on reaching a contest rather than making any contact with McNeil.
"Dane was doing what he needs to do, which is getting in a position to try and get up the ground and spoil," Longmire told reporters on Monday.
"There was a last-minute change of direction and unfortunately accidents happen in football."
