Lord Sewel, who drew up the convention setting out that Westminster should not "normally" legislate in devolved areas, said Brexit was a "major constitutional adjustment" that meant the UK Government could "act on its own initiative".
The former Labour life peer, who played a central role in developing Scotland's devolved system of government, said Brexit legislation was not a "power grab" or a constitutional crisis. MPs will debate the "validity of the Sewel Convention" in an emergency debate on Monday.
But Lord Sewel said the "size and scale" of Brexit meant the UK Government was justified in legislating without the support of MSPs, telling the BBC that the current row was "not a constitutional crisis" and was being used to "seek political advantage".
"There is that 'not normally' phrase in the convention which does I think clearly recognise the possibility that something quite out of the ordinary would happen, which would mean the UK parliament would be required to legislate in a devolved matter even without the permission of the Scottish Parliament," he said.
"I think we're all pretty well agreed that Brexit and leaving the EU is a major constitutional adjustment. We don't live in normal times, in other words.
"Both sides can have an argument on this. But I would tend to fall back on the one that the size and the scale of the change that's envisaged and being brought about because of Brexit does put it in a class of its own, and requires the possibility that the UK government would act on its own initiative, without necessarily the approval of the Scottish government."
He added: "You get a major crisis, of course - and Brexit is a major crisis - and these things get stretched to their limits. But it's also worth remembering that it is just a convention.
"It is not unknown for political parties to seek political advantage over these sort of issues, and there's a fair bit of that going on. It's not a constitutional crisis."
Responding to the comments, a UK Government spokeswoman said: "The EU Withdrawal Bill is about ensuring that the whole of the United Kingdom has a functioning statute book on exit day. As Lord Sewel has confirmed, the UK Government is proceeding entirely in line with the devolution settlement.
"The Sewel Convention sets out that UK Government will not normally legislate in devolved areas without consent. As both we, the Scottish Government and now Lord Sewel acknowledge, these are not normal times.”
Lord Sewel resigned from the House of Lords in 2015 after being filmed allegedly taking drugs with prostitutes.