* Scotland makes case on final day of Supreme Court case
* Says decision to trigger Brexit must go through parliament
* Wales: govt can't use executive powers to "crucify" rights
By Estelle Shirbon and Michael Holden
LONDON, Dec 8 (Reuters) - The British government cannot ignore Scotland's wishes by kicking off the Brexit process without going through parliament, Scotland's chief legal officer told the United Kingdom's Supreme Court on Thursday.
The court is hearing an appeal by the government against a ruling last month that it requires the assent of the British parliament to trigger Article 50 of the EU's Lisbon Treaty -- the first formal step towards quitting the bloc -- and cannot simply use executive powers.
The devolved government of Scotland, where a majority voted against leaving the European Union, argues that it would be wrong for the British government to use executive powers to take the momentous step of triggering Article 50.
"That would by-pass an important constitutional requirement of the United Kingdom," Lord Advocate James Wolffe told the Supreme Court on the fourth and final day of the appeal hearing.
Under a constitutional mechanism known as the Sewel Convention, the British parliament must seek consent from the Scottish parliament when it makes laws that have an impact on policy areas that are devolved to the Scottish government.
Wolffe argued that Brexit would impact on devolved matters, and that meant the London parliament should be involved.
"A bill which determined to withdraw the United Kingdom from the European Union would engage the convention because of the effects that it would have with regard to devolved matters," he said.
This would not be the case if the central government acted unilaterally, he said.
The Supreme Court is expected to deliver its ruling in January.
At stake for the government is its plan to invoke Article 50 by the end of March, which could be jeopardised by lengthy parliamentary debates. Ministers also believe some lawmakers could try and water down their policies on the terms of Brexit.
The United Kingdom as a whole voted to leave the EU by 52 to 48 percent, but while England and Wales voted for Brexit, Scotland and Northern Ireland opted to remain in the EU.
The Scottish government is run by the Scottish National Party, which opposes Brexit and is strongly critical of Britain's ruling Conservative Party.
Scotland's First Minister Nicola Sturgeon has vowed to do everything she can to stop Scotland being taken out of the EU against its will, even raising the possiblity of a second referendum on independence from the United Kingdom.
Richard Gordon, the legal officer for the devolved Welsh government, told the Supreme Court that the Brexit vote had split the United Kingdom into four parts.
"The point is this. It is almost the most divisive political event that has happened over the last several decades. Who is going to judge what happens next? According to law ... it must be parliament," he said.
Gordon said that while the government did have executive powers to make foreign treaties that did not mean it could use these to "dispense with laws...or to crucify human rights." (Editing by Angus MacSwan)