After yesterday's overwhelming Commons vote to pass the bill to trigger Article 50, attention now turns to the House of Lords, with pundits of all shades and stripes asking whether the unelected members of the upper chamber have the temerity to defy their elected counterparts.
At first glance, the bare statistics look a little worrying for Theresa May and the Leave brigade. The Government has already been defeated 16 times in the Lords during this Parliamentary session, which only began in May. Over the past five Parliamentary years, the Government's nose has been blooded 130 times.
Most of the defeats are, in truth, relatively minor setbacks. Last April, for example, peers voted down a Government amendment to the Housing and Planning Bill that would have enabled parish councils to appeal local authority planning permission decisions to the Secretary of State.
However there have been some rather bigger reversals in the not-too-distant past. In October 2015, for example, peers voted against the then-Chancellor George Osborne's proposals for welfare cuts, sending them back to the lower chamber and leaving Osborne muttering about "unelected Labour and Lib Dem Lords" defying the will of the people.
Will the Lords be equally defiant again, and take a hardline on the most sensational British political issue in decades?
Remainers will certainly hope so, particularly given the Tories don't actually have a majority in the House of Lords. The Lib Dems, who have recast their own identity around opposing Brexit, have 104 peers - compared to just eight MPs in the Commons.
But it's important to get things in perspective and remember that the Lords cannot block Article 50 indefinitely – in other words, stop Brexit dead in its tracks. For all the warnings in the right-wing press about the Lords 'blocking' Brexit, it doesn't actually have the power to do so.
What peers do have, however, is the power to bounce the bill back to the Commons with amendments which might delay the triggering process, causing huge frustration for the Government - although if the Lords uses this power it risks incurring the wrath of Mrs May, and reigniting calls for its abolition.
Lord Green, chair of Migration Watch UK and a cross-bench peer in the upper chamber, told talkRADIO: "What the Lords has is the power to amend. If they amend the bill and vote in favour of an amendment by a majority, it goes back to the Commons where it has to be considered.
"If it's voted down [in the Commons] it goes back to the Lords. If the Lords insists on the amendment, a game of ping pong can sometimes develop. On an issue of this importance, any further delay from the Lords could well develop into a constitutional crisis.
"In that situation the Government could invoke the Parliament Act [which allows the Commons to overrule the Lords] - but the whole thing would be delayed for a year."
Green, who has repeatedly suggested Britain needs to curb the number of migrants entering the country, says he himself will vote in favour of triggering Article 50 as he wishes to respect the will of the people and the outcome of the referendum. He adds that it's unlikely the Lords will get into a constitutional crisis and risk abolition.
"In the House of Lords, the only way you can get an amendment through is when Labour and the Lib Dems combine to defeat the Government," Green told us. "In this case it’s an open question how far the Labour Lords will go because their party in the Commons has voted in favour of the bill.
"Many peers will make up their minds when they see the amendments proposed and most will look at exactly what is proposed before they take a view. They might amend the bill once. But at the end of the day they aren’t going to trigger a head-on clash with the elected house."
Brexiteers up and down the country will hope, and trust, that Lord Green is right. But, given the feisty recent history of the Lords, those expecting the Article 50 bill to sail through the upper chamber, waved on its way by a throng of obliging peers, might be in for an unpleasant surprise.