By William James
LONDON (Reuters) - Prime Minister Boris Johnson is winning his parliamentary battle to pass laws that could allow him to tear up parts of Britain's EU exit treaty, despite a warning from Brussels that doing so would wreck their future relationship.
The Internal Market Bill is aimed at ensuring Britain's four nations can trade freely with one another after leaving the European Union.
But the government says that requires creating powers to override part of the withdrawal treaty it signed with Brussels - a breach of international law it says is necessary to protect Northern Ireland if ongoing talks fail.
WHAT HAPPENS NEXT?
The bill must pass through both houses of the British parliament to become law -- first the House of Commons, where Johnson's Conservative Party has an 80-seat majority, and then the House of Lords, the upper chamber, where it does not have a majority.
The bill has passed its most difficult test in the Commons and will finish its journey through the lower house on Monday or Tuesday next week.
After this it will undergo scrutiny in the House of Lords.
SO IT ALL DEPENDS ON THE LORDS?
The bill is not being fast-tracked and will take most of October and November to consider.
This means it will not be law either before an EU end-of-September deadline to withdraw the plan, or Johnson's Oct. 15 deadline for a deal with the EU.
The negotiations around either of these deadlines, if successful, could remove the need for the bill's most contentious parts.
This puts the immediate focus back on negotiations with Brussels, where the EU has not yet taken a formal decision on what to do next in light of Johnson's refusal to withdraw the bill.
A senior EU diplomat said: "The timetable for the passage of the bill does provide a welcome space for constructive engagement on the concerns raised by the UK” and so a decision on possible EU legal action will be delayed until early October.
CAN'T THE HOUSE OF LORDS STILL BLOCK THE BILL?
Many members of the upper house have criticised the bill, including Conservatives, but their primary role is to amend and improve legislation, not to block it on principle.
While there is precedent for the Lords blocking legislation, deciding to do so on this bill would provoke a constitutional row, and such a move is currently seen as unlikely.
The House of Lords is more likely to seek to amend the bill to remove or dilute certain parts, or insert additional checks and balances. The amendments would go back to the House of Commons for approval -- probably in early December.
If Johnson's lower-house majority holds firm, the bill could bounce back and forth between the two chambers until either a compromise is found or the government attempts to pass it without House of Lords approval.
WHY DOES BRITAIN WANT TREATY-BUSTING POWERS?
The government says the powers are a safety net to protect peace in Northern Ireland if negotiations with the EU on how to manage cross-border trade fail.
The EU wants to make sure the open border with Ireland doesn't act as a back door into the bloc for goods. Britain wants to make sure goods flow freely between Northern Ireland and the rest of the United Kingdom.
WHAT CONCESSIONS HAS THE GOVERNMENT MADE?
Johnson has so far made two concessions.
Firstly he promised parliament a vote on any decision to use the treaty-breaking powers created by the bill -- a compromise that snuffed out a rebellion within his own party.
Secondly, he has also committed to referring any dispute with the EU to the resolution mechanism set out in the Withdrawal Agreement "in parallel" to using the treaty-busting powers unilaterally.
(Reporting by William James, additional reporting by John Chalmers in Brussels; Editing by Toby Chopra)