Elaborating on your question of May 5, regarding Mentor / Assessor actions during a game; may I extend the question to cover Assignors?
I am of the opinion, having done some research, that an Assignor cannot and should not, for example, replace a less-than-adequate AR during the course of a match. To me, this at a minimum interferes with the Referee’s authority over his/her crew during the match, and also opens the door to a perception that the officials can be replaced until the hosting organization gets the result that they want.
The context for this is that the ARs and even the Referees are very inexperienced, perhaps working their first few games, and so a reasonable observer could agree that the performance of an AR (or Referee) was, in fact, inadequate. It seems to me that the Assignor (and through him/her, the sponsoring organization) can: change future assignments … including the next game, provide instruction or mentoring, etc.. But once a game has begun the crew cannot be altered except by the referee who may dismiss an assistant for the reasons cited in the Laws.
And perhaps the Assignor should take additional care in the selection of crews.
I am hoping you could confirm or correct my interpretation. I have administrative responsibilities related to assignors in my state
USSF answer (May 26, 2010):
Once the match begins, only the referee has the power to relieve an assistant referee or fourth official of his or her duties. No assignor, no referee administrator of any sort or level, no instructor, no assessor or any other person has this right. And if the referee does decide to do without the person being removed, the game must be officiated in line with the guidelines given in the Referee Administrative Handbook — available for download from http://www.ussoccer.com and published here many times.