British Prime Minister Theresa May is free to officially notify the EU that the UK intends to leave after the Queen granted the Brexit bill royal assent.
Following a turbulent passage through both houses and a drawn out court battle, May is expected to take the historic step of starting the process of leaving the 40-year union.
Speaking in the House of Commons at the beginning of the week, May said she would trigger Article 50 "before the end of the month" and it is expected she will do so in the last week of March.
The prime minister has described it as a "defining moment" for the country but the negotiations that will take place with the EU over the next two years promise to be bitter and bloody.
Key players on both sides will now need to set to work thrashing out a Brexit deal alongside a free trade deal that will govern the UK's future relationship with the remaining 27 members of the EU.
Talks between the two sides are not likely to begin in earnest until June. The EU must issue a formal response to May's formal Article 50 notification and then will need around eight weeks to draw up the full guidelines.
The remaining 27 EU members will then need to formally issue a list of negotiating topics and red lines - the earliest they are expected to decide this is at an extraordinary summit in early May.
The bill's passing into law follows a difficult day for the government on Wednesday in which ministers were accused of "driving towards a cliff-edge with a blindfold on".