§1. Fatalia legis, that is, the time limits established by law for extinguishing rights, cannot be extended nor validly shortened unless the parties request it.
§2. Before the judicial or conventional time limits lapse, however, the judge can extend them for a just cause after the parties have been heard or if they request it; the judge, however, can never shorten those limits validly unless the parties agree.
§3. Nevertheless, the judge is to take care that such an extension does not overly prolong the litigation.
Source: Code of Canon Law (Vatican.va)