LONDON (Reuters) - British lawmakers will debate legislation underpinning the government s plan to leave the European Union this week, the latest stage in an arduous journey through parliament. The first two days of debate in the current stage of the process will be held in parliament on Nov. 14 and 15. A total of eight days of debate are planned during this  Committee Stage , used to make changes to the government s proposed wording of the bill. Formally known as the European Union (Withdrawal) Bill, the legislation will then face several more stages of approval in the lower house of parliament, and must also make its way through a multi-stage process in the upper house. Both chambers must agree on the wording before it can become law. What is the bill and what does it do? The legislation serves two main functions: 1. Repealing the 1972 European Communities Act which made Britain a member of the European Communities, forerunner to the European Union. This effectively ends Britain s EU membership. 2. Transferring the existing body of EU law into British law. This is designed to provide legal certainty about the complex process of leaving.  Why is it controversial? The bill has faced criticism from opposition lawmakers, campaign groups and members of May s Conservative Party. Brexit is still divisive in Britain after a referendum in June last year, and many people, including some lawmakers, want to retain as much of the country s current EU membership as possible. Others would like to reverse the vote. May runs a minority government, which has a slim 13-seat working majority in the 650-seat parliament thanks to a deal with a small Northern Irish party.  A rebellion of seven or more Conservative lawmakers could see her lose a vote in parliament and forced into making concessions. The objections are mainly based on two themes: 1. The power for the government to amend EU laws as they are brought onto the British statute book. These are often referred to as  Henry VIII  powers after the 16th century English monarch who ruled by proclamation. The government says it needs to be able to fix the wording of laws to ensure they work correctly after Brexit. For example, where a law refers to an EU institution which will no longer have jurisdiction in Britain, the law must be changed to point to the correct British equivalent.  Critics say the bill gives ministers too much power to make changes, and creates the potential for policy shifts to be implemented without full parliamentary scrutiny. The process through which the government would make the changes already exists and is known as  secondary legislation . It does allow for some degree of scrutiny by lawmakers, but would not submit changes to the full legislative process.  2. The bill does not contain a provision for parliament to vote on the final Brexit deal. The government has promised lawmakers they will get a  meaningful vote  on the outcome of negotiations in Brussels to decide the terms of Britain s exit and its future relationship with the bloc. As it currently stands, this vote will be on whether to accept the terms of the deal, or reject it and walk away without a deal. But critics says the promise of a vote should be written into the bill. Some also say that it should give lawmakers more options than the current  take it or leave it  vote. This could mean an option to send Britain back to the negotiating table. What has happened so far? The bill cleared its first parliamentary hurdle in September when, after two days of debate, lawmakers voted 326 to 290 in favor of the principles of the bill.  Although the government won the vote, several Conservatives indicated they were unhappy with the details of it, and said they wanted to see concessions during the next stage.  What happens next? The first two days of the  Committee Stage  have been scheduled for Tuesday and Wednesday but the remaining six days have not yet been scheduled.  Any lawmaker can submit changes for consideration. So far, 186 pages of so-called  amendments  have been submitted. The list will be scrutinized by parliament s deputy speaker, whittled down and grouped according to subject. The amendments to be considered will be announced at the start of each day s debate. The first two days will focus on the part of the bill that repeals the 1972 European Communities Act, the retention, conversion and interpretation of existing EU laws, and EU rights.   At the end of the debate over each group of amendments, some will be put to a vote. If supported by a majority of lawmakers, the changes will be made to the bill. They can still be reversed. Once all the groups of amendments have been debated, the bill is reprinted to include any amendments passed and it moves on to the next stage in the process. Which is ...? The bill will be subject to several more stages of votes in the lower chamber and the upper chamber of parliament. The entire process will take months to complete, and there is no target end date. Report stage:  Any amendments voted by the house at committee stage will pass to report stage. This is a new opportunity to add amendments. The speaker of the house oversees this process. Third reading:  This takes place immediately after report stage. It usually lasts an hour and is a general discussion of the bill followed by a vote. No amendments can be made. House of Lords:  The bill passes to the unelected upper chamber of parliament, the House of Lords. Lords can put forward their own amendments, each of which will be discussed and decided on in turn. If the lords agree to any amendments, the bill passes back to the House of Commons for its approval. Ping Pong: If the bill passes back to the commons, they debate and vote on the lords  amendments. No new amendments can be introduced. In theory the bill can continue passing back and forth between the lords and commons until the final bill is agreed upon. Royal assent: Once the bill has been agreed by both houses of parliament, it is given royal assent, when the queen formally agrees to make the bill into an Act of Parliament. 
Factbox: Divided, rebellious UK parliament takes on May's Brexit plan