OECD Convention : Article 9 : Mutual Legal Assistance

Each Party shall, to the fullest extent possible under its laws and relevant treaties and arrangements, provide prompt and effective legal assistance to another Party for the purpose of criminal investigations and proceedings brought by a Party concerning offences within the scope of this Convention and for non-criminal proceedings within the scope of this Convention brought by a Party against a legal person. The requested Party shall inform the requesting Party, without delay, of any additional information or documents needed to support the request for assistance and, where requested, of the status and outcome of the request for assistance.
Where a Party makes mutual legal assistance conditional upon the existence of dual criminality, dual criminality shall be deemed to exist if the offence for which the assistance is sought is within the scope of this Convention.
A Party shall not decline to render mutual legal assistance for criminal matters within the scope of this Convention on the ground of bank secrecy.