Article 20

1. [States] Any State which is party to the Paris Convention or which is a member of the Organization, and in respect of which patents may be granted, either through the State's own Office or through the Office of another State or intergovernmental organization, may become party to this Treaty.

2. [Intergovernmental Organizations] Any intergovernmental organization may become party to this Treaty if at least one member State of that intergovernmental organization is party to the Paris Convention or a member of the Organization, and the intergovernmental organization declares that it has been duly authorized, in accordance with its internal procedures, to become party to this Treaty, and declares that:
(i) it is competent to grant patents with effect for its member States; or
(ii) it is competent in respect of, and has its own legislation binding on all its member States concerning, matters covered by this Treaty, and it has, or has charged, a regional Office for the purpose of granting patents with effect in its territory in accordance with that legislation.
Subject to paragraph 3, any such declaration shall be made at the time of the deposit of the instrument of ratification or accession.

3. [Regional Patent Organizations] The European Patent Organisation, the Eurasian Patent Organization and the African Regional Industrial Property Organization, having made the declaration referred to in paragraph 2(i) or (ii) in the Diplomatic Conference that has adopted this Treaty, may become party to this Treaty as an intergovernmental organization, if it declares, at the time of the deposit of the instrument of ratification or accession that it has been duly authorized, in accordance with its internal procedures, to become party to this Treaty.

4. [Ratification or Accession] Any State or intergovernmental organization satisfying the requirements in paragraph 1, 2 or 3 may deposit:
(i) an instrument of ratification if it has signed this Treaty; or
(ii) an instrument of accession if it has not signed this Treaty.