Section 87 — Liability for excess by the offender
English translation
In a case where there has been instigation to commit an offence, advertisement or announcement to commit an offence, or support in the commission of an offence, the instigator, the advertiser or announcer, or the supporter shall be liable only to the punishment prescribed for the offence instigated, advertised or announced, or supported, even though the person instigated has acted beyond the scope of the instigation, or the offender has acted beyond the scope of the advertisement or announcement, or beyond the scope of the support.
But if the excess could be foreseen as a result that would ordinarily arise, the instigator, the advertiser or announcer, or the supporter shall be liable for the result of that excess as well.
In a case where the offender must receive heavier punishment by reason of the result arising from the commission of the offence, the instigator, the advertiser or announcer, or the supporter shall receive heavier punishment by reason of that result only if he knew or ought to have known that such result would occur.
This English translation is provided for reference only and has not yet been firm-verified — always rely on the Thai original.
Firm annotation
Section 87, closing the Title on Principals and Supporters in Book 1, limits the derivative liability of the instigator, advertiser and supporter when the actual offender overshoots. The default rule is protective: each is liable only for the offence within the scope of what they instigated, advertised, or supported, not for the offender's excess. Two qualifications follow. First, if the excess was foreseeable as an ordinary result of what they set in motion or assisted, they answer for that excess too. Second, where an aggravating result makes the offender liable to heavier punishment, that heavier punishment reaches the instigator, advertiser, or supporter only where they knew or ought to have known the result would occur. The section applies across sections 84, 85 and 86 and keeps accessory liability tethered to the accessory's own foresight and knowledge.
Why this matters in practice
For anyone charged as an instigator, advertiser, or supporter, this section is a shield and a limit: liability normally stops at the offence within the scope of what they set in motion, and it does not automatically follow the offender into more serious conduct. The two openings for the prosecution are foreseeability, that the excess was an ordinary result to be expected, and knowledge, actual or constructive, of an aggravating result. The defence should therefore focus on what the accused actually intended to bring about and what they could reasonably foresee, since an unexpected escalation by the principal does not by itself transfer the heavier penalty.
Frequently asked questions
Is an instigator liable if the offender does more than was asked?
Under section 87, generally no; the instigator is liable only for the offence within the scope of the instigation. But they are liable for the excess if it could be foreseen as an ordinary result.
When does a supporter get the heavier punishment for an aggravating result?
Under section 87, a supporter, instigator, or advertiser receives heavier punishment for an aggravating result only if they knew or ought to have known that such result would occur.