Section 19(3) of the Local Government Act 2001 prescribes that a casual vacancy on a local authority is to be filled by the co-option of a person to fill the vacancy, subject to such person being nominated by the same registered political party who nominated for election or co-option the member who caused the casual vacancy, or where the person causing the casual vacancy was a non-party candidate at his or her election to the local authority, the vacancy is to be filled by the co-option by the local authority of a person to fill the vacancy in accordance with such requirements and procedures as may be set out in its standing orders, except in circumstances where paragraphs (c) or (d) or (e) of section 19 (1) of the Act apply.
Paragraph (c) of section 19(1) of the Act relates to Article 25 (procedures after nomination), Article 28 (death of a candidate) and Article 124 (person elected for more than one local electoral area) of the Local Elections Regulations 1995, paragraph (d) relates to circumstances prescribed in regulations made under section 27 of the Local Government Act 2001, under which regulations have not been made; and paragraph (e) relates to section 15 (1) of the Local Elections (Petitions and Disqualifications) Act 1974 , dealing with an order of the court relating to a petition declaring that a person was not duly elected as a member of a local authority or was not qualified for membership of a local authority or that the whole or part of a local election was void.
