Section 5(3) of the Trade Marks Act 1994 mirrors Article 8(5) of Council Regulation (EC) 40/94 which implements the Community trademark system. Regulation (EC) 40/94 became operational on 1 April 1996. To date, Article 8(5) of the Regulation has not been applied in practice. Nevertheless, it should be noted that the reference to "use without due cause" reflects a general principle of law, i.e. a "rule of reason", as a consequence of which the use of a sign, which would in principle constitute trademark infringement under Article 8(5), may be considered justified in exceptional circumstances. In Article 8(5) of the Regulation, this principle is reflected by the wording "without due cause", implying that in exceptional cases, use of a sign which is identical or similar to a registered mark for dissimilar goods or services may be permissible, even where the other elements of trademark infringement apply. It should be stressed that, as a rule, the exception under the rule of reason will not apply. Jurisprudence at the level of the Member States has shown that defences on the basis of the rule of reason have never been successful. In order to successfully invoke the rule of reason, some Member States' jurisdictions require that the user of the sign must prove either that he has an imperative need to use the sign and that he cannot reasonably be obliged to renounce on such use, or that such user proves that he has an own right to use the sign.
