Hernandez's contract provided for him to receive that amount if he participated in 90 percent of the team's voluntary offseason workouts.
"On behalf of all players, it is our responsibility to protect the rights in the collective bargaining agreement," the union said in a statement. "We are not tone-deaf to what the allegations are in this case, but for the benefit of all players, there are important precedents here we must protect."
The Patriots cut Hernandez after he was arrested on June 26 and before he was charged with murder later that day. He pleaded not guilty and is being held without bail in the shooting death of Odin Lloyd, a friend whose body was found June 17 near Hernandez's house. The union believes Hernandez earned the bonus before his arrest.
Patriots owner Robert Kraft indicated he disagreed.
"It's simple," he said Tuesday. "You can look at our history. We honor all our contracts and we expect the people who sign them to honor their part of the contract."
Asked if he felt Hernandez didn't do that, Kraft said, "We honor our contracts and we expect the people on the other side to do the same."
Last year, Hernandez signed a five-year, $40 million contract extension through the 2018 season. The contract, a copy of which was obtained by The Associated Press, includes an $82,000 bonus if Hernandez "successfully completes" at least 90 percent the possible offseason workouts at the team's facility. The bonus would have been paid "on or about" Aug. 1.
The NFL's collective bargaining agreement allows teams to recoup bonus money when a player is incarcerated. The Patriots cut Hernandez before the bonus, if earned, was due.
Hernandez was indicted last Thursday on first-degree murder and weapons charges in the death of Lloyd, whose bullet-riddled body was found in an industrial park about a mile from the ex-player's North Attleborough, Mass., home.
Prosecutors say Hernandez orchestrated Lloyd's killing because he was upset at him for talking to people Hernandez had problems with at a nightclub days earlier.
Kraft said that since he bought the Patriots before the 1994 season, "we've had probably over 2,000 people playing here and I think, by and large, we've done a pretty good job. If you look at the last four years I don't think we had any off-field incidents. So we're as diligent as we can be.
"We know what we want to achieve, yet, when people go outside this building, it's like those of you who have children," Kraft told reporters. "Once they get to a certain age, you can't control all their activities."
He also said that "every year in all of our businesses, we recalibrate what we are doing to make sure we're staying fresh and on top of things, and once you stop doing that, you'll perish."
The NFL, Kraft said, is "the most competitive business I've ever been involved in and so we have reviewed everything. We've been very diligent (in) the way we look at things and we'll try to do things as best as we can to achieve the results we want."
The Patriots are "a microcosm of the world," he said. "All kinds of things are going to happen. We do our best to hope that (players) understand they're in a unique place. Playing in the NFL is a privilege and we hope they're wise and mature enough to make sure they know how to take advantage of that."
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