Cyflwyniad
Ddydd Llun 18 Mehefin cynhaliwyd dadl frys yn Nhŷ'r Cyffredin ar ddilysrwydd Confensiwn Sewel. Gofynnwyd am y ddadl gan Blaid Genedlaethol yr Alban (yr SNP) am nad oedd digon o amser wedi'i neilltuo i drafod materion yn ymwneud â datganoli wrth i Aelodau Tŷ'r Cyffredin ystyried gwelliannau'r Arglwyddi i Fil yr Undeb Ewropeaidd (Ymadael) (“y Bil Ymadael”). Ar 15 Mai, roedd Senedd yr Alban wedi gwrthod rhoi cydsyniad deddfwriaethol i ddarpariaethau’r Bil Ymadael.
Pete Wishart (Perth a Gogledd Swydd Perth) (SNP)
Is the right hon. Gentleman not ashamed, embarrassed and appalled that we have only 15 minutes to discuss these critical devolution issues? These amendments were designed in the House of Lords, but we, the directly elected Members, have not had the opportunity to debate them. Is he not ashamed of himself?
Mr Lidington
No. I think that the Government allowed perfectly adequate time for debate on these issues. As the hon. Gentleman knows, these questions on devolution matters have been discussed in great detail by me, my Ministers and officials, and the Welsh and Scottish Governments and legislatures for many months. As I hope to explain, the Government have made very substantial compromises to address precisely the concerns raised by both Scotland and Wales. I am pleased that the Welsh Government have accepted the merits of the compromise we proposed and reached an agreement.
Confensiwn Sewel
Nodir Confensiwn Sewel yn Neddf yr Alban 1998 a Deddf Llywodraeth Cymru 2006, fel y'u diwygiwyd gan Ddeddf yr Alban 2016 a Deddf Cymru 2017, yn y drefn honno. Mae'r Deddfau'n nodi na fydd dim ynddynt yn effeithio ar bŵer Senedd y DU i ddeddfu ar gyfer y deddfwrfeydd datganoledig “But it is recognised that the Parliament of the United Kingdom will not normally legislate with regard to devolved matters without the [their] consent”. Er mai dim ond yn ddiweddar y cafodd ei rhoi mewn statud, mae Confensiwn Sewel wedi gweithredu'n ymarferol ers 1999 ac mae'n gymwys i Gynulliad Gogledd Iwerddon hefyd.
Yn 2017, yn ei ddyfarniad ynghylch a ddylid ymgynghori â Senedd y DU cyn rhoi Erthygl 50 i adael yr UE ar waith, dyma a nododd y Goruchaf Lys ynghylch Confensiwn Sewel:
It therefore plays an important role in the operation of the UK constitution. But the policing of its scope and operation is not within the constitutional remit of the courts. The devolved legislatures do not have a veto on the UK’s decision to withdraw from the EU.
Ym mis Mehefin 2017 cydnabu Llywodraeth y DU y byddai'n gofyn am gydsyniad y deddfwrfeydd datganoledig ar gyfer y Bil Ymadael. Ar 15 Mai, gwrthododd Senedd yr Alban roi cydsyniad ar gyfer y Bil Ymadael mewn pleidlais a gefnogwyd gan Aelodau o'r blaid Lafur, y Democratiaid Rhyddfrydol a'r Blaid Werdd. Daeth Llywodraeth Cymru i gytundeb rhynglywodraethol â Llywodraeth y DU ar welliannau i’r Bil Ymadael ac yn dilyn hynny, pleidleisiodd y Cynulliad i roi cydsyniad ar gyfer y Bil yr un diwrnod.
Cyflwynodd Senedd yr Alban a Chynulliad Cenedlaethol Cymru “Filiau Parhad” a fyddai'n trosglwyddo cyfraith yr UE sydd o fewn y cymhwysedd datganoledig i gyfraith ddatganoledig. Cyfeiriwyd y ddau Fil i'r Goruchaf Lys gan y Twrnai Cyffredinol er mwyn cadarnhau a oeddent o fewn cymhwysedd. 
Datganiad Ysgrifennydd Gwladol yr Alban
Ysgogwyd y ddadl frys hefyd gan Ddatganiad Ysgrifennydd Gwladol yr Alban, y Gwir Anrhydeddus David Mundell AS, a wnaed ar 14 Mehefin. Wrth gloi, dywedodd Mr Mundell:
We are now therefore faced with the reality that the Scottish Parliament has not given consent for this critically important legislation that provides certainty across the UK. That is not a situation that any of us would have chosen. It is not, however, a crisis, nor is it unforeseen. While the devolution settlements did not predict EU exit, they did explicitly provide that in situations of disagreement the UK Parliament may be required to legislate without the consent of devolved legislatures.
In any situation, agreement is our aim, and we will continue to seek legislative consent, take on board views and work with the Scottish Government on future legislation, just as we always have done. We on this side of the House have compromised. We have made every effort to reach agreement. We have sought consent. Now we are legislating in line with the Sewel convention to ensure the whole of the United Kingdom leaves the EU with as much legal certainty as possible. That is what people and businesses in Scotland need.
Roedd hyn yn diystyru Confensiwn Sewel ym marn y gwrthbleidiau. Dywedodd Paul Sweeney AS (Llafur):
The Secretary of State was responsible for taking the Scotland Act 2016 through this place, he was responsible for inserting the Sewel convention into the legislation, and now he is the person responsible for trampling all over that convention that underpins the devolution settlement.
Dywedodd Ian Blackford AS (SNP):
Section 28(7) of the Scotland Act 1998 confirms that Westminster retains its unlimited sovereignty, and arguably it can never relinquish that, but the devolution settlement provides through the Sewel convention that the legislative power will not be used if there is disagreement and the devolved legislatures do not give consent. Today’s statement effectively turns Sewel on its head by saying that, if there is disagreement—that is, no consent on a legislative consent motion—the UK Government can proceed to legislate. This is an extremely serious development in UK Government thinking, and it risks the security of the devolution settlement.
Y Ddadl Frys
Agorwyd y ddadl gan Ian Blackford AS ar ran yr SNP. Dywedodd fod Confensiwn Sewel yn anymarferol a nododd:
Under the constitutional rules, this Government should not proceed without the Scottish Parliament’s consent. By constitutional convention and invariable practice since 1999, the Bill should not complete its Westminster stages in its current form without that consent. Despite the murmurings of the current Secretary of State, the Scotland Office stated back in 2005 that the UK Government “considers that the continuation of the Convention is vital to the success of devolution”.
What has changed? The only thing that has changed is that the Scottish Parliament has not given its consent and the UK Government, showing utter disrespect, have decided to proceed.
Roedd Brendan O'Hara AS (SNP) yn pryderu bod San Steffan yn gosod cynsail ar gyfer y math yma o sefyllfa o wrthod pleidlais fwyafrifol yn Senedd yr Alban pryd bynnag y bydd anghytundeb.
Soniodd Ian Murray AS (Llafur) am dryloywder. Yn ystod hynt Bil yr Alban yn 2015, dywedodd ei fod wedi cyflwyno gwelliannau i roi Cydbwyllgor y Gweinidogion ar sail statudol i ganiatáu i gofnodion ac agendâu gael eu cyhoeddi'n gyhoeddus. Anogodd Canghellor Dugiaeth Caerhirfryn:
[…] to give a clear commitment that every single piece of communication that has happened in the JMC with regards to the devolution amendments is published. I shall tell him why he should do that. While this whole process is secret and while people are kept in the dark about who said what and who agreed to what, all we get is: this is a power grab, or this is a powers bonanza. The people of Scotland then have to decide which one is the most appropriate. As the compromise was made, I want to know, and the people of Scotland want to know, how far apart the two sides are.
Awgrymodd Jamie Stone AS, (y Democratiaid Rhyddfrydol) y byddai rhyw fath o gorff trawsbleidiol o Aelodau Seneddol y Meinciau Cefn ac Aelodau o Senedd yr Alban yn adeiladol o ran gweithrediad y ddwy Senedd yn y dyfodol.
Dywedodd Liz Saville-Roberts AS (Plaid Cymru) y byddai angen i bob un o lywodraethau cenedlaethol y DU gydweithio'n aeddfed wrth ddatblygu fframweithiau cyffredin ar gyfer y DU gyfan. “It should not be a case of one country asset-stripping powers away from the others to impose a once-size-fits-all England-first framework across all the UK’s countries.” Nododd hefyd mai dim ond ar ffurf cytundeb rhynglywodraethol y câi San Steffan ei rwymo’n wleidyddol, tra byddai y llywodraethau datganoledig yn wynebu cyfyngiadau cyfreithiol.
Ystyriodd Joanna Cherry CF AS (SNP) ystyr y geiriau “not normally” yng nghyd-destun Confensiwn Sewel:
The Sewel convention is a rule, not merely a description of practice, so the word “normally” has to be understood as an exception to the rule. According to the principles of legal interpretation, we make exceptions to a rule either where the underlying rationale for the rule does not apply or where there is some overriding competing principle. The rationale for the Sewel convention is protection of devolved autonomy. It is not clear to me […] why the protection of devolution should be suspended by the Brexit vote.
Atebodd Canghellor Dugiaeth Caerhirfryn, y Gwir Anrhydeddus David Lidington AS, ar ran Llywodraeth y DU:
The IGA [Intergovernmental Agreement] states the commitment of both the UK Government and the Welsh Government to proceed by agreement. It makes it clear that the Sewel convention will be fully respected, and we have made it clear that, despite the fact the Scottish Government and the Scottish Parliament have so far rejected a legislative consent motion, we will act in our future dealings with the Scottish authorities in the same way as we propose to act in relation to Wales, by observing in full the political commitments into which we have entered under the intergovernmental agreement.
Erthygl gan Alys Thomas, Gwasanaeth Ymchwil Cynulliad Cenedlaethol Cymru
