Unfair competition or antitrust covers all actions aimed at promoting sales and increasing business profits, but which in the normal course of business must be regarded as impermissible. Abuse of any unique position is prohibited. In general, there is no question of unfair competition if one profits from someone else's efforts, knowhow or insight even if that inflicts a disadvantage on the other party. So a business concept can be pinched. The starting point is after all the principle of freedom of business and profession. In the case of concomitant circumstances of a more serious nature, however, there might be a question of unlawful acts. In common parlance, those circumstances come down to the fact that the competition is, or has been, playing tricks behind your back. So make protection of your IP rights a priority. Besides the general statutory provisions on unlawful acts (6:162 BW), misleading advertising can also play an important role in the case (article 6:194 Dutch Civil Code et al).
Because of the constitutionally protected right of free speech, the courts are generally reluctant to assume unfair competition on the grounds of misleading advertising. Exaggeration is inherent to the promotional nature of advertising and the general public will not be put off track just like that, that is the idea. The turning point is where the average consumer would not have bought your competitor's product or service if the consumer had known of negative aspects that your competitor remained silent on.