Artikel 37

1. This Convention shall not affect the undertakings given in any other existing or future international Convention, whether bilateral or multilateral, between two or more of the Contracting Parties, on extradition or any other form of mutual assistance in criminal matters.
2. The Contracting Parties may not conclude bilateral or multilateral agreements with one another on the matters dealt with in this Convention, except in order to supplement its provisions or facilitate application of the principles embodied in it.
3. Should two or more Contracting Parties, however, have already established their relations in this matter on the basis of uniform legislation, or instituted a special system of their own, or should they in future do so, they shall be entitled to regulate those relations accordingly, notwithstanding the terms of this Convention.
Contracting Parties ceasing to apply the terms of this Convention to their mutual relations in this matter shall notify the Secretary-General of the Council of Europe to that effect.