The RSPB has applied to the Supreme Court for permission to appeal against a major wind farm development which it believes would hit seabird colonies.
The Scottish Government gave consent to four major wind farms in the Firth of Forth and the Firth of Tay in 2014, but the RSPB launched a judicial review.
The charity initially won a court victory but it was later overturned, clearing the development and prompting the RSPB to seek a further appeal.
Scotland's Court of Session last month refused the application for the case to be sent to the Supreme Court, but the RSPB has now applied directly to the UK's highest court.
The charity said it recognises the role renewable energy has in reducing emissions but the current project could lead to major declines in the population of gannets, puffins and kittiwakes.
The Scottish Government said it is "focused on creating a sustainable energy future for Scotland".
The wind farm projects could generate enough power to supply the equivalent of 1.4 million homes.
RSPB Scotland director Anne McCall said: "RSPB Scotland has not taken this decision lightly, however our concerns with the manner in which Scottish ministers' took their decisions in 2014 remain undiminished.
"Additionally, the issues of the case and the recent inner house judgment extend beyond simply the impacts of these developments on important seabird populations. Therefore due to the implications of this latest decision for many aspects of our work, we felt we had no choice but to apply to the Supreme Court.
"We are hopeful that our application is successful and that we are granted leave to appeal so these important issues of public interest can be considered in detail by the Supreme Court."
A Scottish Government spokesman said: "We note the RSPB's decision, which comes after the Court of Session in Edinburgh ruled, decisively, in favour of Scottish ministers and subsequently dismissed the RSPB's application for permission to appeal to the UK Supreme Court.
"The Scottish Government is focused on creating a sustainable energy future for Scotland so that Scotland can meet its obligations to fight climate change, and thereby tackling a key threat to marine ecosystems."