FFA are introducing the trial is aimed at "improving the behaviour of team officials primarily towards match officials but also opposition team officials whilst in the technical area".

The A-League and W-League are the first top-flight domestic competitions in the world to trial the system which will come into affect this weekend.

Coaches and officials will first receive a warning for "unacceptable behaviour" such as persistent questioning of referee decisions and entering the field of play.

A yellow card will be produced for "irresponsible behaviour" which includes dissent, acting provocatively and deliberating entering the technical ara of the opposing team.

Finally, violent conduct, using offensive language or entering the field of play to interfere with an opposing player will see a coach dismissed for "irresponsible behaviour".

Garriock, who played 134 games for the Matildas and received just one red card in her 18-year playing career, said there is a reason the trial is a world first.

"Had anyone in Europe thought it was a good idea than they'd be doing it, for Australia to do it first is a very interesting decision," Garriock said.

"It just allows the referees extra power which they love. The game isn't about the coaches it's about the players and this is somewhat taking the coach's power away to coach.

"It will be very interesting to see how it's received."

A-League and W-League head Greg O'Rourke defended the decision and said the trial was a positive and spectator-friendly move.

"Referees already have a process which is by way of conversation to coaches to warn them before removing them from the technical area after poor behaviour," O'Rourke said.

"Essentially this trial will visualise those steps and as such better communicate to fans that the referees are giving the coaches and others formal warnings.

"It will help fans and viewers better understand the issues that match officials face on a weekly basis and help promote respect towards them.

"Importantly it will send a strong message throughout the game at grassroots level that poor behaviour towards match officials and opposition team officials is unacceptable and carries consequences."

The trial is part of International Football Advisory Board's global "Play Fair" initiative which aims to make football fairer, more attractive by promoting players and officials as positive role models for society.

United lost its season-opener against Melbourne Victory last week and have the bye in round two, before hosting Garriock's former side Sydney FC at McKellar Park on November 12.