Now I think I got it: The relevant article of the Spanish Penal Code, explained and commented:
Some bits translated (the original is in the link, it’s only four paragraphs long, followed by some commentary):
- Anyone who performs any act that infringes on the sexual freedom of another person without that person’s consent shall be punished by imprisonment for a term of one to four years as a perpetrator of sexual assault. Consent shall only be understood to exist when it has been freely expressed through acts which, in view of the circumstances of the case, clearly express the will of the person.
- In any case, acts of sexual aggression are considered sexual aggression when they are carried out using violence, intimidation or abuse of a situation of superiority or vulnerability of the victim, as well as those performed on persons who are sensory deprived or whose mental situation is abused and those that are carried out when the victim’s will is annulled for any reason.
- Not relevant here, IMO.
- The sentencing body, reasoning it in the sentence, and provided that there is no violence or intimidation, nor that the victim’s will is annulled for any reason, and provided that the circumstances of article 180 do not concur, may impose a prison sentence half as long as stated above or a fine of eighteen to twenty-four months, taking into account the minor nature of the act and the personal circumstances of the guilty party (bolding mine).
I believe that point 4 shows that for “minor assaults” the tribunal may skip prison altogether (not just grantig probation, which is usually given for sentences under two years for first time offenders) substituting prison with a fine. The reference to the duration between 18 - 24 months means the fine shall be proportional to the income or wealth of the perpetrator, who still will be considered guilty, just the sentence will be lighter.
Sorry it took a while and excuses for the mess with the Mexican law.