Nicola Sturgeon raised the specter of another Scottish independence referendum after Britain's Supreme Court ruled Tuesday that the devolved assembly in Edinburgh did not need to be consulted on triggering Brexit.
"This raises fundamental issues above and beyond that of EU membership," the Scottish first minister said.
"Is Scotland content for our future to be dictated by an increasingly right-wing Westminster government with just one MP [lawmaker] here," she asked. "Or is it better that we take our future into our own hands?"
"It is becoming ever clearer that this is a choice that Scotland must make," she added.
Scots rejected independence in 2014 but Sturgeon's ruling Scottish National Party (SNP) said Britain's decision to leave the EU last June—against Scottish voters' wishes—has created the conditions for another independence referendum.
Sturgeon said the British government is politically obliged to consult the devolved assemblies on exiting the European Union, regardless of the Supreme Court ruling.
May has said Britain would quit the EU single market and impose immigration limits when it leaves the bloc and has promised to take Scotland into account in the process.
But Sturgeon was scornful about those pledges in the wake of the court ruling.
"The claims about Scotland being an equal partner are being exposed as nothing more than empty rhetoric and the very foundations of the devolution settlement that are supposed to protect our interests... are being shown to be worthless," she said.
She said she would press on regardless and present a motion in the Scottish parliament to vote on the triggering of Article 50, which starts the Brexit process.