Short answer. Slander by deed is defamation committed by an act rather than by words — anything that casts dishonour, discredit or contempt on another person. Physical injuries punishes the harm done to the body; slander by deed punishes the humiliation, which is why a slap in public can be either one.
What the law says
shall be imposed upon any person who shall perform any act not included and punished in this title, which shall cast dishonor, discredit or contempt upon another person
Revised Penal Code, Article 359 — Slander By Deed. Read the full provision →
Defamation without words
Libel is written, oral defamation is spoken, and Article 359 of the Revised Penal Code catches the rest: an act that casts dishonour, discredit or contempt on another person. Slapping someone in front of onlookers, spitting on them, stripping or tearing at their clothing in public, chasing them out of a gathering — the conduct is punished because of what it says about the victim in front of others, not because of any wound. The article is expressly residual: it applies to acts not included and punished elsewhere in the title on defamation. If the conduct is already libel or oral defamation, this article does not add a second charge.
Serious or not serious
The article splits the offence in two. Where the act is of a serious nature the penalty is heavier; where it is not, the penalty drops to arresto menor or a small fine. Seriousness is judged from the circumstances — the social standing of the parties, whether the humiliation was public, the place, the occasion, and the relationship between them. The peso figures printed in the article are those set by Republic Act No. 10951 (2017), which revised the fines throughout the Revised Penal Code. Older reproductions still show the 1930 amounts, so a fine quoted from an out-of-date source will be wrong.
Where physical injuries takes over
The two crimes look at the same slap from opposite ends. Physical injuries asks what damage the body suffered and how long the victim was incapacitated or needed medical attendance; slander by deed asks whether the act was meant to and did humiliate. If the assault caused real injury and the dominant intent was to hurt rather than to shame, the charge is physical injuries. If there was no meaningful injury but there was public humiliation, slander by deed fits. Where the intent was to shame and injury also resulted, prosecutors sometimes charge in the alternative and let the evidence sort it out. Intent, and the presence of an audience, are what decide it.
How a complaint is brought
Defamation is a private crime in an important sense: the offended party's own complaint drives it, and the case cannot be prosecuted on a stranger's initiative. A civil claim for moral damages runs alongside the criminal one, and in practice the damages matter more to complainants than the short penalty does. Because the prescriptive periods for light offences are very short, delay is fatal — a complaint sat on for months may no longer be filed at all. Nobody can promise how a case will end. This page is general legal information rather than advice on your situation; to have an incident assessed, you can book a consultation.