Factbox: What does a 'meaningful vote' on Brexit really mean?

LONDON (Reuters) - A row over how much say Britain's parliament should have over the Brexit process is set to reach its conclusion on Wednesday as lawmakers finalise the wording of the laws that will end the country's membership of the European Union next year.

After more than 250 hours of debate, one major issue remains.

Prime Minister Theresa May's government has promised to give parliament a meaningful vote on the final Brexit deal it negotiates with Brussels, but what does that actually mean?

On the table are two similar technical definitions of what that promise means: one proposed by the government, and one proposed by a pro-EU member of May's Conservative Party, Dominic Grieve.

 

Parliament will decide which version to approve later on Wednesday in what is expected to be a very tight vote. The vote would be politically damaging for May to lose, and could make a 'no deal' Brexit less likely.

Below is a summary of what is agreed, and where differences remain.

AGREED

- Once the government has agreed a Brexit deal with the EU, it will present that deal in parliament and allow lawmakers to approve or reject it.

- If that deal is rejected by parliament, or if the government decides no deal is possible, or if a deal has not been reached by Jan. 21, 2019, the government has to come up with a new plan of action and present it to parliament.

NOT AGREED

- The government says parliament should be allowed to debate the plan on next steps, but not to amend the plan. They argue this would bind the government's hands in negotiations, which May and her team say is unacceptable.

- The rival amendment says parliament should be able to debate the plan on next steps and amend it if necessary. Its backers argue that this would not bind the government's hands, and is necessary to make the vote on the final Brexit deal truly meaningful.

WHY DOES IT MATTER?

The real power of the rebel amendment is political.

It paves the way for lawmakers to explicitly endorse an alternative to May's plan.

If parliament does that it would be hugely damaging for May and make it very difficult for an already weakened leader to follow through with her long-standing promise to leave the EU without an agreed exit deal unless Brussels agrees to a "good deal".

Anything that decreases the probability of a 'no deal' scenario will be welcomed by most businesses, who fear the disruption of an unmanaged and abrupt exit.

(Reporting by William James; Editing by Matthew Mpoke Bigg)