Agreements and decisions of trade associations that infringe Article 4 of the Law No. 4054 on the Protection of Competition ("Competition Law") are invalid and unenforceable with all their consequences (Article 56 of Competition Law). Article 4 of Competition Law prohibits agreements, concerted practices and decisions that restrict competition.

The parties to a restrictive agreement cannot enforce their contractual rights before Turkish courts, since agreements that violate the law are invalid (Article 27 of the Turkish Code of Obligations). Courts are required to ex officio look into whether the agreement is invalid and unenforceable. A party that has already fulfilled its obligations under the restrictive agreement can seek a relief from the court to reclaim the performance.

Not all types of Article 4 violations invalidate the whole agreement. Severable provisions such as non-compete clauses in block-exempted vertical agreements would not render the entire agreement invalid, to the extent they can be severed from the rest of the agreement. However, agreements which per se aim to violate competition law such as cartel agreements would be invalid in their entirety.

The relevant legislation does not make a reference to Article 6 of Competition Law, which prohibits abuses of dominant position. The issue of whether the 'null and void' status applicable to agreements that fall foul of Article 4 may be interpreted to additionally cover contracts entered into by infringing dominant companies is a matter of ongoing controversy. However, contracts that give way to or serve as a vehicle for an abusive contract may be deemed invalid and unenforceable because of violation of Article 6 of Competition Law.