Fundamental rights and the use of force
Fundamental rights bind everyone, including private guards, through the horizontal effect of rights and through specific legislation. The relevant rights: right to liberty and security (no arbitrary detention), privacy (Article 22 Constitution, Article 8 ECHR - covers body searches, filming, data), inviolability of the home (Article 15 Constitution - a guard cannot enter a private dwelling without consent or legal authority), freedom of movement, non-discrimination, and presumption of innocence.
Use of force: Belgian law has no general "use of force ladder" statute for guards, but the principles are legality, necessity, proportionality, subsidiarity (force only when no less intrusive means works), and minimum force for the minimum time. Force is justified only under self-defence (imminent, unlawful attack, proportionate response) or necessity (avert a greater harm). A guard may never use force to punish, to obtain a confession, or to enforce a rule where no danger exists. Weapons are restricted: firearms only for specific licensed categories (e.g., cash-in-transit) under strict conditions.
Traps: (1) "the guard may search a bag to protect the shop" - no, only with consent or legal basis; (2) "restraint is always allowed" - restraint must be necessary, proportionate, and the person monitored; (3) confusing self-defence with retaliation; (4) ignoring that disproportionate force turns the guard into the offender.
Worked example: An aggressive visitor raises a fist. The guard steps back, speaks calmly, calls for backup, and only uses a controlled hold if the fist comes down. Rule of thumb: can I do this less intrusively? If yes, do that. If force is used, stop as soon as the danger ends and record everything.
Know also the prohibition of inhuman treatment and the duty to protect vulnerable persons in custody.