Don't know the exact term, but I can explain the concept (actually it has to do with the previous sentence):
It means that the nature of injunctive reliefs (medidas cautelares) - that is, to protect a right - is not directly related to the evaluation of the truth in the question involved. That's why they say that judges (the ones who are granting this injunctive relief)are not requested to analyze the absolute certainty of the existence of the right, but the probability of that existence. The "medida cautelar" is a protective measure; your text refers to the "juicio de verdad" as opposing the purpose of the injunctive relief; it probably implies that the "medida cautelar" has to be granted, to protect a right, while at the same time judges go on analyzing facts, evidences, etc, to find out the truth.
Hope it helps.