The International Covenant on Economic, Social and Cultural Rights was adopted and opened for signature, ratification and accession by General Assembly resolution 2200A (XXI) of December 16, 1966 (entry into force on January 3, 1976, in accordance with article 27).
For the full text of the Covenant, go to: http://www2.ohchr.org/english/law/pdf/cescr.pdf

International Covenant on Economic, Social and Cultural Rights (1966)
Article 8
1. The States Parties to the present Covenant undertake to ensure:
(a) The right of everyone to form trade unions and join the trade union of his choice, subject only to the rules of the organization concerned, for the promotion and protection of his economic and social interests. No restrictions may be placed on the exercise of this right other than those prescribed by law and which are necessary in a democratic society in the interests of national security or public order or for the protection of the rights and freedoms of others;
(b) The right of trade unions to establish national federations or confederations and the right of the latter to form or join international trade-union organizations;
(c) The right of trade unions to function freely subject to no limitations other than those prescribed by law and which are necessary in a democratic society in the interests of national security or public order or for the protection of the rights and freedoms of others;
(d) The right to strike, provided that it is exercised in conformity with the laws of the particular country.
2. This article shall not prevent the imposition of lawful restrictions on the exercise of these rights by members of the armed forces or of the police or of the administration of the State.
3. Nothing in this article shall authorize States Parties to the International Labour Organisation Convention of 1948 concerning Freedom of Association and Protection of the Right to Organize to take legislative measures which would prejudice, or apply the law in such a manner as would prejudice, the guarantees provided for in that Convention