Content by way of rebuttal is the most demanding and interesting feature of a good debate. The skilful speaker is able to counter or undermine the argument of their opponent. After the first proposition speech, each speaker must spend some time attacking the case by the other side. A speaker who undermines their opposition while consolidating their own defence should be rewarded. A speaker who ignores the strength of their opposition's case must be penalised.
Points of information are particularly useful for rebuttal.
A team that fails to rebut will always lose. Perceptive analysis of the logic behind opposing arguments is a powerful strategy. Speakers should always be ready to pounce on unsubstantiated assertions, logical fallacies and contradictions within the opposing case. After content and style, the strategy of a team's overall approach will be judged. Some of these 'technical' criteria can sink otherwise excellent teams.