During a Tournament that I was helping to run at a games club, a difference of opinion was formed over units being 'corrupted' while already in combat. The organiser thought those units stopped attacking/defending, but I thought they still continued to attack/defend in their corrupted state. Neither of us found anything in the FAQ, so checked the rulebook. (Original). My argument was taken from the 1st paragraph under 'CORRUPTION'. "Corrupt cards cannot be declared as attackers or defenders". His argument was taken from the 2nd paragraph. "Other effects can corrupt an opponent's forces, thereby preventing those forces from attacking or defending".

Obviously a corrupted unit cannot be declared as an attacker/defender - no argument - so it boils down to the word 'prevents'. Having played the game for a much longer time than the others, I was positive I had seen comments about this in the early forums, but since they are now massive in size, it was difficult to find them. The latest FAQ does not mention this, but what does the new rulebook state? What is the official ruling? Cheers!

You are correct. Corrupting a unit after it has been declared as attacker or defender won't affect its participation in that combat.

Your opponent ignored the sentence right before the one he based his argument on. The rulebook just says there that units can not only be corrupted through their own effects, but by other cards' effects too.