Trosglwyddodd adran 13 o Ddeddf Llywodraeth Cymru 2006, fel y’i diwygiwyd gan Ddeddf Cymru 2017, bwerau penodol oddi wrth Ysgrifennydd Gwladol Cymru i Weinidogion Cymru i wneud darpariaeth ar gyfer cynnal etholiadau’r Senedd. Cyn pob un o etholiadau’r Senedd, caiff Gorchymyn Cynulliad Cenedlaethol Cymru (Cynrychiolaeth y Bobl) 2007, sy’n nodi’r ffordd y bydd yr etholiad ac ymgyrch yr etholiad yn cael eu cynnal ac sy’n cynnwys darpariaeth ar gyfer her gyfreithiol, ei adolygu a’i ddiwygio er mwyn adlewyrchu unrhyw newidiadau mewn polisi neu ddeddfwriaeth ers yr etholiad diwethaf.
Section 13 of the Government of Wales Act 2006, as amended by the Wales Act 2017, transferred particular powers from the Secretary of State for Wales to the Welsh Ministers to make provision for the conduct of Senedd elections.   Ahead of each Senedd election the National Assembly for Wales (Representation of the People) Order 2007, which sets out the manner in which the election and election campaign is conducted and includes provision for legal challenge, is reviewed and amended to take account of any policy or legislative changes since the last election.