Rajlich's first sin was to ignore the ICGA rule that
Each program must be the original work of the entering developers. Programming teams whose code is derived from or including game-playing code written by others must name all other authors, or the source of such code, in their submission details. Programs which are discovered to be close derivatives of others (e.g., by playing nearly all moves the same), may be declared invalid by the Tournament Director after seeking expert advice.The phrase 'close derivative' requires a subjective evaluation. The most blatant violation of the rule would be to take an existing engine, do nothing more than change its name, and enter it in competition. It's common sense that Rybka wouldn't have won four consecutive world titles 'by playing nearly all moves the same' as its competitors.
Rajlich's second sin was to ignore the ICGA investigation.
The ICGA regards Vasik Rajlich’s violation of the abovementioned rule as the most serious offence that a chess programmer and ICGA member can commit with respect to his peers and to the ICGA. During the course of the investigation and upon presentation of the Secretariat’s report Vasik Rajlich did not offer, despite repeated invitations from the ICGA to do so, any kind of defence to the allegations, or to the evidence, or to the Secretariat’s report [...]
For these two sins, the ICGA punished Rajlich in every way available to it -- stripped of his titles, 'banned for life from competing in the World Computer Chess Championship or any other event organized by or sanctioned by the ICGA', and asked to return all trophies and prize money -- punishments which, in my opinion, far exceed the gravity of the offense. Add to this the damage to Rajlich's reputation and commercial activities, and it is conceivable that the affair will evolve into a civil lawsuit.
I wonder if Levy and the ICGA realize how much their action has diminished the value and reputation of their WCCC. Knowing that the results can be changed at any time in the future, who can take these events seriously? It is entirely possible that one of the newly promoted winners in the years 2007-2010 will one day be judged to have committed the same offense as Rajlich; then the former no.3 placeholder in the tournament will become the 'winner'. I can even imagine that all participants in an event will eventually be disqualified, as though the event had never taken place. As things were, WCCC events got little attention from the chess world. Now they will get even less. Well done, ICGA, (not).