LGBT groups have criticised the "distressing" court ruling on the Scottish Government's gender reform Bill.
On Friday (December 8) the Court of Session judged the UK Government was within its rights to effectively veto the Gender Recognition Reform (Scotland) Bill, despite it being approved by MSPs at Holyrood.
The Bill, which seeks to make it easier for transgender people to be legally recognised in their acquired gender, was blocked by Scottish Secretary Alister Jack using a Section 35 order.
Now, the First Minister is facing a decision on whether to appeal the ruling at the Court's Inner House, and potentially the Supreme Court.
LGBT Youth Scotland said the decision by Judge Lady Haldane was "deeply distressing" and disregards "years of advocacy" for a fairer society.
Dr Mhairi Crawford, chief executive at the charity, said: “The obstructing of simple administrative changes will massively impact trans young people, who should have the right to live as themselves without scrutiny.
“We call on the Scottish Government to stay resolute in their ambition to ensure the best outcome for trans young people by swiftly challenging this ruling. No law should deny individuals, especially young people, the right to gain legal gender recognition aligning with their identity.
“Everyone should have the right to live their lives, regardless of the background, sexual orientation or gender identity.”
The Gender Recognition Reform (Scotland) Bill has proved one of the most controversial pieces of legislation to ever go before Scottish Parliament.
The Scottish Government proposed changes to the process for trans people to receive a Gender Recognition Certificate, which enables them to be issued with a new birth certificate under their acquired gender.
It would streamline the current process - which has been described as "lengthy and intrusive" - including cutting the time a person has to live in their acquired gender from two years to three months, and changing the minimum age of applicants from 18 to 16.
However, gender-critical feminist groups have raised concerns about the impact on women's rights, particularly on replacing a medical diagnosis for gender dysphoria with self declaration, also known as self-ID.
A spokesperson for the LGBT Youth Scotland Trans Right’s Youth Commission said: “We all want to be seen for who we are, both by the law and those we love; however, this is something that is a struggle for trans people.
“Gender recognition reform seeks to lift this weight off our shoulders, and it is incredibly disheartening and upsetting to hear the court ruling. We hope that with time this will be realised, allowing all of us to be equally respected.”
Stonewall also spoke out against the Court of Session ruling, saying it means "more uncertainty" for trans people in Scotland.
In a statement, the LGBT charity said: "We’re disappointed that the Court of Session in Scotland has found in favour of the UK Government’s unprecedented decision to use Section 35 to block the Gender Recognition Reform Bill from Royal Assent.
"This Bill was one of the most debated in the Scottish Parliament’s history and was passed by a resounding majority of MSPs drawn from all major Scottish parties.
"This unfortunately means more uncertainty for trans people in Scotland, who will now be waiting once again, to see whether they will be able to have their gender legally recognised through a process that is in line with leading nations like Ireland, Canada and New Zealand.
"Whatever happens next in discussions with the UK and Scottish Governments on this matter, Stonewall will continue to press all administrations to make progress on LGBTQ+ rights in line with leading international practice."