Article 21: Right to take part in government

Everyone has the right to take part in the government of his country, directly or through freely chosen representatives.

Everyone has the right to equal access to public service in his country.

The will of the people shall be the basis of the authority of government; this will shall be expressed in periodic and genuine elections which shall be by universal and equal suffrage and shall be held by secret vote or by equivalent free voting procedures.

Definitions of the right to take part in government

The right to freedom of movement is enshrined in 
Article 21 of the Universal Declaration of Human Rights.

The right is enshrined in Article 25 of the International Covenant on Civil and Political Rights:

Every citizen shall have the right and the opportunity, without any of the distinctions mentioned in article 2 and without unreasonable restrictions:
(a) To take part in the conduct of public affairs, directly or through freely chosen representatives;
(b) To vote and to be elected at genuine periodic elections which shall be by universal and equal suffrage and shall be held by secret ballot, guaranteeing the free expression of the will of the electors;
(c) To have access, on general terms of equality, to public service in his country. 

In its General Comment No 25 of 1996, the Human Rights Committee comments on the right to take part in government: http://www2.ohchr.org/english/bodies/hrc/comments.htm.

The right is also contained in Articles 7, 8 and 11 of the Convention on the Elimination of All Forms of Discrimination against Women:

Article 7
States Parties shall take all appropriate measures to eliminate discrimination against women in the political and public life of the country and, in particular, shall ensure to women, on equal terms with men, the right:
(a) To vote in all elections and public referenda and to be eligible for election to all publicly elected bodies;
(b) To participate in the formulation of government policy and the implementation thereof and to hold public office and perform all public functions at all levels of government;
(c) To participate in non-governmental organizations and associations concerned with the public and political life of the count.

Article 8
States Parties shall take all appropriate measures to ensure to women, on equal terms with men and without any discrimination, the opportunity to represent their Governments at the international level and to participate in the work of international organizations.

Article 11
1. States Parties shall take all appropriate measures to eliminate discrimination against women in the field of employment in order to ensure, on a basis of equality of men and women, the same rights, in particular:
(a) The right to work as an inalienable right of all human beings;
(b) The right to the same employment opportunities, including the application of the same criteria for selection in matters of employment;
(c) The right to free choice of profession and employment, the right to promotion, job security and all benefits and conditions of service and the right to receive vocational training and retraining, including apprenticeships, advanced vocational training and recurrent training;
(d) The right to equal remuneration, including benefits, and to equal treatment in respect of work of equal value, as well as equality of treatment in the evaluation of the quality of work;
(e) The right to social security, particularly in cases of retirement, unemployment, sickness, invalidity and old age and other incapacity to work, as well as the right to paid leave;
(f) The right to protection of health and to safety in working conditions, including the safeguarding of the function of reproduction.
2. In order to prevent discrimination against women on the grounds of marriage or maternity and to ensure their effective right to work, States Parties shall take appropriate measures:
(a) To prohibit, subject to the imposition of sanctions, dismissal on the grounds of pregnancy or of maternity leave and discrimination in dismissals on the basis of marital status;
(b) To introduce maternity leave with pay or with comparable social benefits without loss of former employment, seniority or social allowances;
(c) To encourage the provision of the necessary supporting social services to enable parents to combine family obligations with work responsibilities and participation in public life, in particular through promoting the establishment and development of a network of child- care facilities;
(d) To provide special protection to women during pregnancy in types of work proved to be harmful to them.
3. Protective legislation relating to matters covered in this article shall be reviewed periodically in the light of scientific and technological knowledge and shall be revised, repealed or extended as necessary.

The Convention on the Rights of Persons with Disabilities contains this right in Article 29:

States Parties shall guarantee to persons with disabilities political rights and the opportunity to enjoy them on an equal basis with others, and shall undertake to: 
(a) Ensure that persons with disabilities can effectively and fully participate in political and public life on an equal basis with others, directly or through freely chosen representatives, including the right and opportunity for persons with disabilities to vote and be elected, inter alia, by: 
(i) Ensuring that voting procedures, facilities and materials are appropriate, accessible and easy to understand and use; 
(ii) Protecting the right of persons with disabilities to vote by secret ballot in elections and public referendums without intimidation, and to stand for elections, to effectively hold office and perform all public functions at all levels of government, facilitating the use of assistive and new technologies where appropriate; 
(iii) Guaranteeing the free expression of the will of persons with disabilities as electors and to this end, where necessary, at their request, allowing assistance in voting by a person of their own choice; 
(b) Promote actively an environment in which persons with disabilities can effectively and fully participate in the conduct of public affairs, without discrimination and on an equal basis with others, and encourage their participation in public affairs, including: 
(i) Participation in non-governmental organizations and associations concerned with the public and political life of the country, and in the activities and administration of political parties; 
(ii) Forming and joining organizations of persons with disabilities to represent persons with disabilities at international, national, regional and local levels.

The right is also contained in Article 13 of the African Charter on Human and Peoples' Rights:

1. Every citizen shall have the right to participate freely in the government of his country, either directly or through freely chosen representatives in accordance with the provisions of the law.
2. Every citizen shall have the right of equal access to the public service of his country.
3. Every individual shall have the right of access to public property and services in strict equality of all persons before the law.