Felly mae'r Cwnsler Cyffredinol am gyflwyno tystiolaeth lafar ac ysgrifenedig ynghylch defnyddio'r Uchelfraint i roi rhybudd i adael yr Undeb Ewropeaidd dan Erthygl 50 Cytuniad yr Undeb Ewropeaidd, gan ddiystyru rhai o ddarpariaethau Deddf 2006 ac addasu pwerau'r Cynulliad Cenedlaethol a Gweinidogion Cymru.  Ar ben hynny, mae'r Cwnsler Cyffredinol am gyflwyno tystiolaeth ynghylch cyfyngiadau pŵer yr Uchelfraint i effeithio ar statudau sydd â statws "cyfansoddiadol" megis Deddf 2006 (fel y cyfeiriwyd ati gan y Llys Adrannol ym mharagraffau 43-44, 82 ac 88 y dyfarniad), a'r defnydd o'r Uchelfraint i ddiystyru egwyddorion cyfansoddiadol sy'n sail i ddatganoli yn y Deyrnas Unedig. Edrychodd y Llys Adrannol ar bwysigrwydd yr egwyddorion cyfansoddiadol ym mharagraffau 82-84 y dyfarniad.
The Counsel General therefore wishes to make written and oral submissions on the use of the Prerogative to give notice to withdraw from the European Union under Article 50 TEU, thereby overriding certain provisions of GoWA 2006 and altering the powers of the National Assembly and the Welsh Ministers.  Further, the Counsel General wishes to make submissions on the limits of the Prerogative power to affect statutes which have “constitutional” status such as GoWA 2006 (as addressed by the Divisional Court at paragraphs 43-44, 82 and 88 of its judgment), as well as the use of Prerogative to override the constitutional principles underpinning devolution in the United Kingdom. The Divisional Court addressed the significance of constitutional principles in paragraphs 82-84 of its judgment.