The once-great Repeal Bill is the centrepiece of the Queens Speech. The Bill will repeal the European Communities Act (ECA) 1972, formally severing the UK's legislative ties with the European Union, and placing the huge body of EU law onto the UK statute book. It will lay the legislative foundations for Brexit.
The purpose of this rather large cut and paste job is to provide continuity and certainty, ensuring no EU law disappears unintentionally or without a UK one to replace it.
But it is not quite that simple. A straight cut and paste would result in large numbers of laws that do not function in the UK after Brexit. Transferring an EU law that refers to the European Medicines Agency is no good if we are no longer part of the European Medicines Agency. So, the Repeal Bill also gives the Government powers to amend legislation and 'correct' laws that are no longer relevant or refer to EU institutions.
It's here it begins to get contentious.
The opposition have warned of 'sweeping legislative powers', which enable a government to continue to change important laws without the formal procedure - slipping in non-essential changes in through the back door. Recognising the sensitivities, the Government's Great Repeal Bill White Paper (published in March) committed to time limiting these powers, but there is also an important role for the rest of Parliament in applying sufficient scrutiny.
Another potential flashpoint is the role of the devolved administrations in Wales, Scotland and Northern Ireland. The Repeal Bill may result in Westminster making changes in policy areas that Edinburgh, Cardiff and Belfast see as beyond their remit. The Queen's Speech addresses the importance of all four nations co-operating, but in practice there are already concerns about a lack of quality engagement.
Finally the role of the European Court of Justice (ECJ) will need to be clarified. The UK courts will be looking to the Bill for instruction on how to interpret ECJ case law, what happens to cases to certain cases already in progress and a raft of detailed legal questions regarding past and future judgements.
If Labour had won the election, they would have scrapped the Bill, and replaced it with an EU Rights and Protections Bill. In reality, any Labour bill would have needed to do much the same thing; it performs an imperfect but important function. It's yet to be seen if Labour will try and oppose the Repeal Bill once it's introduced, Parliamentary arithmetic must make it enticing as a high-profile target. But it's a dangerous game - the Bill is designed, first and foremost, to give certainty and to avoid a big cliff edge. Something very similar will need to be passed by March 2019.
Perhaps more likely is the tabling of amendments to the Bill. It's here that opposition in Parliament could try to impose its 'type of Brexit' on the Government or constraint their flexibility. It could table amendments that mean the Repeal Bill only comes in to force if certain provisions are met.
The Government has its work cut out. It will need to build a constructive dialogue with Parliament and Devolved Administrations, making the case for the Bill and giving further assurances that new powers will not be abused. But Parliament has an important role too, it needs to pick its battles on Brexit.