Fumus bonis iuris or fumus boni iuris translated literally means " smoke of good law ", but in its semantic sense it should be understood as appearance or external appearance of law. Fumus bonis iuris is the appreciation of good law, which in criminal proceedings is translated in which an investigated fact has the character of a crime and the probability that the accused had participated in its commission. In it, there are well-founded elements of conviction that may compromise the criminal responsibility of the person under trial, with the probability that a criminal conviction will fall on said person that will lead to the deprivation of their liberty for a long period of time.
It is also known as the verisimilitude of the right invoked; the " fumus bonis iuris " together with the " periculum in mora " (danger in delay), are the conditions or assumptions required to obtain and protect a precautionary measure, the latter is the precautionary decision executed during a trial and presents characteristics peculiar according to the type of process to be cautious. When neither of these two assumptions exist, then there is neither the need nor the legality to apply a precautionary measure.
The fumus bonis iuris constitutes the first requirement that the judge must verify when faced with the obligation to issue a precautionary order. In simple words, it translates into the existence of a trial or reasoning where the court in charge of decreeing it, foresees the solid probabilities that the applicant for the measure will benefit from the provisions of the final court decision. It is nothing more than a subjective and largely discretionary assessment of the judge on the appearance that there are interests, protected by the law, totally summary and superficial.
