The First Minister said "mindsets at Westminster" have not shifted to accommodate the creation of the Scottish Parliament during an address in Edinburgh to mark the 20 years of devolution.
And the SNP leader again warned that Westminster politicians must not be allowed to prevent a second referendum on independence which she is seeking to stage next year.
"Devolution has transformed politics in Scotland," the SNP leader said at the Law Society of Scotland event.
"It has put beyond any doubt that Scotland is a distinct political community within these islands.
"But at the same time devolution has had virtually no effect on mindsets at Westminster. Over the past three years we've seen from the UK Government an aggressive assertion of the idea of the supremacy of the Westminster Parliament.
"And as a result we are not simply facing the prospect of being removed from the EU against our will, there is also the growing possibility of a catastrophic "no deal" exit as hardliners in the Tory party get ready to take control."
Sturgeon said the creation of the Scottish Parliament had been down to the "democratic deficit" which saw successive Tory Governments elected in th e1980s and impose policies north of the border despite Scots voting Labour.
Ms Sturgeon added: "Now 20 years on we face the most important example of a democratic deficit in Scotland's post-war history.
"The UK Parliament going against the votes of our elected representatives in Parliament and also the votes of the Scottish people in the 2016 referendum - and doing so in a way which pays little or no heed to Scotland's wishes, priorities and values."
Ms Sturgeon has set out plans to stage a second referendum on independence next year, but would require the transfer of power from Westminster which has control over the constitution. Both candidates to become new Tory leader, Boris Johnson and Jeremy Hunt, have rejected this.
But Ms Sturgeon added: "We need to ask ourselves a fairly fundamental question.
"Do we believe that Westminster should have the ultimate right to determine our future regardless of what people in Scotland want?
"Or do we believe, as the Claim of Right, says that people in Scotland have the sovereign right to determine the form of government best suited to our needs. My view is that the paramount principle has to be that decisions about Scotland are best taken by the people who live here.
"We can use that principle as our anchor. It determines that Scotland must have the ability if we so choose to chart a different course and choose a different future.
"In my view a future as an independent country playing our part in the European Union and the wider world."