What is in the Withdrawal Agreement, and why is it so controversial?

With chaos reigning in London, embattled British Prime Minister Theresa May despite two heavy defeats is clinging to the Withdrawal Agreement she negotiated with the EU last November.

Because of those two defeats in the House of Commons, alternative options were sought but ultimately rejected by MPs on Wednesday night, who voted down eight possible solutions.

Given that, Mrs May's deal, battered and bruised as it is, is back on the table ahead of today's round of voting.

Just what is in the Withdrawal Agreement, and why is it so controversial?

Northern Ireland backstop:

Without question, the most contentious aspect of the deal is the protocol relating to Ireland in the case of a no-deal Brexit.

Known as the backstop, it provides that if no long-term trade deal has been agreed by the end of 2020 that avoids a hard border between Northern Ireland and the Republic of Ireland, and if there is no extension to the transition period, then a backstop consisting of "a single customs territory between the (European) Union and the United Kingdom" will be triggered.

The single customs territory, if it were needed, would ensure that completely frictionless trade could continue across the Irish border. Hated by the DUP and the hardline Brexiteers, it is seen a weakening the Union. It remains the main impediment to progress.

Transition:

The deal provides for a 21-month transition period in which the UK will need to abide by all EU rules, but will lose membership of its institutions.

The draft withdrawal agreement says the transition can be extended, but only for a period of one or two years. Originally, it was stated that both the UK and EU must agree to an extension, the EU has since relaxed it stance on this.

Legal provisions:

Under the deal, the UK would remain under the European Court of Justice (ECJ) jurisdiction during the transition, which is also a major bone of contention for hardline Brexiteers.

Also, a joint UK-EU committee would be established to try to resolve any disputes on the interpretation of the withdrawal agreement.

If the backstop is triggered and the UK forms a single customs territory with the EU, the ECJ will not be able to resolve disputes between the UK and EU directly. The whole dispute resolution procedure will be backed up by an arbitration panel.

Fishing rights:

The Withdrawal Agreement provides for a separate deal to be signed to define access to EU fishing in UK waters. "The Union and the United Kingdom shall use their best endeavours to conclude and ratify 'an agreement' on access to waters and fishing opportunities,” the Agreement states.

Money:

The draft agreement sets out the calculations for the financial settlement (or "divorce bill") that the UK will need to pay to the EU to settle all of its obligations.

It is believed the amount involved is £39bn and it will be paid over a number of years.

Movement of people:

UK citizens in the EU, and EU citizens in the UK, will retain their residency and social security rights after Brexit.

Citizens who take up residency in another EU country during the transition period (including the UK of course) will be allowed to stay in that country after the transition.

Anyone that stays in the same EU country for five years will be allowed to apply for permanent residence.