Ed Miliband completely eviscerated Boris Johnson's controversial Internal Markets Bill.
Jaw-dropping moments from his speech, like his (unmet) demand that Johnson approach the dispatch box to defend it, have gone viral.
His speech has been praised for its passion and clarity on why the bill is so bad for the UK.
The Internal Markets Bill threatens to break international law as it will allow Johnson's government to renege on parts of the Brexit agreement they have already drawn up with the EU.
It also returns some devolved powers to Westminster
It is, in Miliband's words, "legislative hooliganism". Along with this, here's 14 of the best lines from his brutal takedown.
1. "The prime minister has said many times he wants to bring unity to the country during his premiership. I therefore congratulate him on having in just one short year united his five predecessors."
Former prime ministers Theresa May, David Cameron, Gordon Brown, Tony Blair and John Major have all spoken out against Johnson's Internal Markets Bill.
2. "Only this prime minister would think taking a wrecking ball to the NI (Northern Ireland) protocol would be the right way to resolve them."
The Northern Ireland protocol is a temporary arrangement Johnson negotiated last October that means there are no checks on goods along the Irish border.
3. "I stood opposite the prime minister’s predecessor but one, David Cameron, as leader of the opposition for five years. I disagreed with him profoundly on many issues but I could never have imagined him coming along and saying we are going to legislate to break international law on an agreement we had just signed less than a year earlier as a country."
4. "This is not an argument about Remain versus Leave, it is an argument about right versus wrong."
5. "This is not just legislative hooliganism, it is hooliganism on the most sensitive of issues."
A major contributor to Brexit's complexity is the possibility that the creation of a hard border between Northern Ireland and the Irish Republic would undermine the Good Friday Agreement, which effectively brokered peace in the area.
6. "The deal the prime minister told us was a triumph. The deal he said was oven-ready. The deal on which he fought and won a general election. [He now says] is far from being oven-ready. It is completely half-baked."
7. "What incompetence. What failure of governance. How dare he try and blame everyone else?"
8. "There is only one person responsible for this. Him. This is his deal, his mess, his failure. For the first time in his life, it's time to take responsibility."
9. "A competent government would never have entered into a binding agreement with provisions it could not live with."
10. "Let us be clear, the very act of passing this bill breaks international law, not just exercising the power."
Northern Ireland secretary Brandon Lewis admitted that the Internal Markets Bill will break international law in a "specific and limited way" by overwriting some of the Brexit agreement signed off on by the government and the EU. Johnson defended the bill, calling it "absolutely vital".
11. "It now turns out that breaking the law specifically and in a limited way is a reasonable defence for this government. We have all heard of self-defence, the alibi defence, the innocence defence. Now we have the Johnson defence."
12. "And what about the prized trade deal with the United States? I know the prime minister thinks he has a friend in president Trump but even he must recognise he must be able to deal with both sides."
Miliband pointed out that House speaker Nancy Pelosi said there will be "absolutely no chance of a US-UK trade agreement passing the Congress" if the UK violates the Northern Ireland Protocol and undermines the Good Friday agreement.
13. "No deal is not some game, it is about the livelihoods of millions of people across our country."
14. "[Johnson] should be focussing on securing a Brexit deal, not breaking international law and risking no-deal. He is cavalier on international law. This is not the serious leadership we need."
You can read a transcript of Miliband's blistering speech in its entirety here.