Pe na fyddem wedi sicrhau'r Cytundeb Rhynglywodraethol, byddai'n Bil ni hefyd wedi bod gerbron y Goruchaf Lys wrth ochr Bil yr Alban, ac mae'n debyg iawn mai'r un peth fyddai'r canlyniad – o fewn cymhwysedd pan basiwyd y Bil gan y Cynulliad, ond nifer o’r darpariaethau bellach yn cael eu hystyried y tu allan i gymhwysedd ddim ond yn sgil effaith Deddf yr Undeb Ewropeaidd (Ymadael) a ddaeth i rym yn ddiweddarach. Mewn geiriau eraill, heb y Cytundeb Rhynglywodraethol ni fyddai ein Bil wedi dod i rym ac ni fyddai bellach modd ei weithredu.
Had we not secured the intergovernmental agreement, our bill too would have been before the Supreme Court alongside the Scottish bill and in all likelihood subject to the same result - within competence when passed by the Assembly but many of its provisions now held to be outside competence due only to the impact of the subsequent enactment of the European Union (Withdrawal) Act. In other words, without the inter-governmental agreement our bill would not yet have been enacted and would now have been rendered inoperable.