Possibility for the Commission (or in certain cases for the national competition authorities) to withdraw the benefit of exemption from the prohibition of Article 101(1) of the EC Treaty, granted to an agreement by a block exemption regulation. The Commission may withdraw the benefit of a block exemption if it considers that specific circumstances, which are mentioned by the relevant block exemption regulation, bring about the need for a closer examination of possible anti-competitive effects of the agreement.

Source: Glossary of terms used in EU competition policy, Antitrust and control of concentrations, European Commission, 2002