For security reasons, all hold baggage is screened.
If during this screening, the security agent suspects the presence of prohibited or dangerous goods, the Brussels Airport Security department is allowed to open your bag or suitcase in pursuance of Regulation (EC) No 300/2008 of the European Parliament and of the Council.
As a rule the passenger is confronted with their baggage. In this case your baggage will be opened in your presence and the security staff will explain to you why an extra search is being performed.
In some cases however a confrontation is not possible (e.g. when the baggage is late). In that case the baggage will be opened by the Chief Security Inspector of Brussels Airport, in the presence of the supervisor of the security agent.
The prohibited or dangerous item, if any, will be removed from the baggage and a three-language document with reference number will be put into the bag or suitcase to inform its owner. In this case you will not know that your bag or suitcase was opened until after you have reclaimed it at your destination.