The genuineness of commodities, such as arrays of filter cigarettes in containers of the type having a closure is ascertained by providing the commodities with identifying indicia prior to their confinement in containers. The containers carry encoded symbols which are supposed to be indicative of the contents of the respective containers. In order to ascertain whether or not the contents of a container are indeed products of the manufacturer or distributor the name and/or the trademark of which appears on the container, the closure is opened or removed, the contents of the container are identified by a detector which monitors the indicia, and the thus obtained signal is compared with the signal which is obtained as a result of decoding the symbol which is applied to the container.