Nigeria

(1) There shall be established for each State of the Federation and the Federal Capital Territory, one or more election tribunals to be known as the National and State Houses of Assembly Election Tribunals which shall, to the exclusion of any Court or Tribunal, have original jurisdiction to hear and determine petitions as to whether
(a) any person has been validly elected as a member of the National Assembly; or
(b) any person has been validly elected as member of the House of Assembly of a State.
... (Sec. 285)

The Commission shall have power to –
(a) organise, undertake and supervise all elections to the offices of the President and Vice-President, the Governor and Deputy Governor of a State, and to the membership of the Senate, the House of Representatives and the House of Assembly of each State of the Federation;
(b) register political parties in accordance with the provisions of this Constitution and an Act of the National Assembly;
(c) monitor the organisation and operation of the political parties, including their finances, conventions, congresses and party primaries;
(d) arrange for the annual examination and auditing of the funds and accounts of political parties, and publish a report on such examination and audit for public information;
(e) arrange and conduct the registration of persons qualified to vote and prepare, maintain and revise the register of voters for the purpose of any election under this Constitution;
(f) monitor political campaigns and provide rules and regulations which shall govern the political parties;
(g) ensure that all Electoral Commissioners, Electoral and Returning Officers take and subscribe the Oath of Office prescribed by law;
(h) delegate any of its powers to any Resident Electoral Commissioner; and
(i) carry out such other functions as may be conferred upon it by an Act of the National Assembly. (Third Schedule, Sec. 15)