Professional Footballers Association chairman Clarke Carlisle has insisted that nobody could have forced Rio Ferdinand to wear a Kick It Out campaign T-shirt ahead of Manchester United's game against Stoke.
Ferdinand, whose brother Anton was the subject of a racial incident with Chelsea captain John Terry last year, refused to promote the anti-racism campaign on Saturday, despite manager Sir Alex Ferguson insisting his player would take part.
After the game, Ferguson described the incident as "embarrassing'' and promised to "deal with it'', but the players' union has defended Ferdinand's right to make a personal protest.
"We will definitely monitor the situation very closely and make sure Rio Ferdinand's rights as a human being, never mind as a footballer, are not undermined in this position," Carlisle told BBC Radio 5 Live. "Everyone has a right to free speech.
"Just like you can't coerce anyone into shaking hands, you can't make somebody wear a T-shirt - although I do personally believe that joining in with the campaign is the best way forward, and then for all these players to get together and put what it is they want down on paper so we together as a union - all the players, one with another - can make those changes and move forward.''
Anton Ferdinand also did not wear the Kick It Out campaign T-shirt before QPR's game with Everton on Sunday.
Information from the Press Association was used in this report