What happened
The Withdrawal Agreement — the legally binding treaty Johnson signed with the EU in October 2019 and which he had promised was an 'oven-ready deal' — included specific provisions on Northern Ireland designed to keep the Irish border open. These required Northern Ireland to remain aligned with EU single market rules for goods.
The Internal Market Bill proposed to give ministers the power to override these provisions by secondary legislation — without Parliament's approval. It was a proposal to break an international treaty the UK had signed ten months earlier, using a mechanism that bypassed Parliament.
Brandon Lewis's statement — 'in a specific and limited way' — became one of the most widely quoted admissions of deliberate illegality by a UK government minister in modern times. Three former Prime Ministers (Major, Blair, and Brown) wrote to The Times to say it was a 'constitutional outrage'. Geoffrey Cox, who had been Attorney General and signed off the original Withdrawal Agreement, called it 'unconscionable'.
The Bill was eventually passed with the offending provisions removed, after the EU threatened trade talks collapse. But the episode illustrated a core characteristic of Johnson's approach to governance: signing agreements he didn't intend to honour, then presenting the problem he had created as the EU's fault.