Joe Freeman tweeted this photo of Portland Trail Blazer Damian Lillard wearing an "I Can't Breathe" warm up shirt.

Shortly after, some of his teammates joined him

LaMarcus Aldridge, Wesley Matthews, Dorell Wright and Will Barton joining Damian Lillard in wearing the 'I Can't Breathe' shirts in warmups. — Trail Blazers (@trailblazers) December 11, 2014

Some NBA players and other athletes are wearing the shirts to support the family of Eric Garner, who died July 17 after a New York City police officer placed him in a choke-hold while Garner was being arrested. A video of Garner's arrest showed him repeatedly gasping "I can't breathe".

Lillard told the Blazers' Casey Holdahl about his reasons for wearing the shirt, including the events surrounding Oscar Grant.

. @Dame_Lillard explains his reasons for wearing an 'I Can't Breathe' shirt pre game in Minnesota http://t.co/LhRBb0j3G3 — Casey Holdahl (@CHold) December 10, 2014

Players are required to wear attire of Adidas, the NBA's official apparel provider, but a league source told ESPN's Jeremy Schaap earlier in the week that the NBA will not fine players who wore the shirts in warm-ups.

Yesterday NBA Commissioner Adam Silver was quoted by Adrian Wojnarowski as saying about the shirts,

"I respect Derrick Rose and all of our players for voicing their personal views on important issues but my preference would be for players to abide by our on-court attire rules."

Last Tuesday most of the LA Lakers wore the shirts before their game with the Sacramento Kings. In a ESPN.com news services article Kobe Bryant was quoted as saying:

"I think it would be a serious disservice to limit this to a race issue. It's a justice issue."

Some of the other NBA players seen wearing the warmup shirts at a recent Cavaliers vs. Nets game were LeBron James, Kyrie Irving, Kevin Garnett, Deron Williams, Jarrett Jack, and Alan Anderson.