Canon 1593

Can. 1593 §1. If the respondent appears at the trial later or responds before a decision in the case, the respondent can offer conclusions and proofs, without prejudice to the prescript of can. 1600; the judge, however, is to take care that the trial is not prolonged intentionally through longer and unnecessary delays.

Can. 1593 §2. Even if the respondent did not appear or respond before a decision in the case, the respondent can use challenges against the sentence; if the respondent proves that there was a legitimate impediment for being detained and there was no personal fault in its not being made known beforehand, the respondent can use a complaint of nullity.