Several Conventions require declarations to be made (compulsory declarations) either in the instrument of ratification itself or in an accompanying document. For instance, under article 2 of the Minimum Age Convention, 1973 (No. 138), a ratifying State must specify in a declaration appended to its ratification, a minimum age for admission to employment or work within its territory. Similarly, under Standard A4.5 (10) of the MLC, 2006, a ratifying State must at the time of ratification specify the branches of social security for which protection is provided to seafarers. If no such declaration is received by the Office, the ratification cannot be registered.

In the case of some Conventions a declaration is needed only where the ratifying State wishes to make use of permitted exclusions, exceptions or modifications (optional declarations). For instance, under article 16 of the Migrant Workers (Supplementary Provisions) Convention, 1975 (No. 143), a ratifying State may by a declaration append to its ratification, exclude either Part I or part II from its acceptance of the Convention. Similarly, under article 3 of the Plantations Convention, 1958 (No. 110), a ratifying State which has excluded one or more Parts from its acceptance of the obligations of the Convention, shall specify in a declaration appended to its ratification the Part or Parts so excluded. A Member which has made use of the option to limit the scope of the Convention’s application to it may subsequently modify, cancel or withdraw such limitation by a further declaration according to the terms of each Convention.

The term ‘declaration’ is also used for the communication made under article 35 of the Constitution by a member State responsible for the international relations of a non-metropolitan territory with a view to notifying the extent to which it undertakes to apply the provisions of a ratified Convention to that territory. The member State concerned may subsequently communicate a further declaration modifying the terms of any former declaration.

Declaration is also the term to designate a special type of Conference resolution where principles of lasting importance are enunciated at the highest level. A declaration is a solemn instrument containing symbolic and political undertakings by the member States. It commits the Organization as a whole and produces legal effects vis-à-vis all its bodies, namely the Governing Body and the Office. To date, the ILO has adopted seven declarations: the Declaration of Philadelphia in 1944, which has since formed an integral part of the Constitution; the Declaration concerning the policy of apartheid of the Republic of South Africa in 1964; the Declaration on equality of opportunity and treatment for women workers in 1975; theDeclaration concerning multinational enterprises in 1977; the Declaration on fundamental principles and rights at work in 1998; the Declaration on social justice for a fair globalization in 2008; and theCentenary Declaration in 2019. With the exception of the Declaration concerning multinational enterprises that has been adopted by the Governing Body, all declarations have been adopted by the Conference.