The US wants rid of NAFTA's dispute settlement mechanism but for Canada it's a red line issue.
Many have compared the UK's repeal of the Corn Laws in 1846 with leaving the European Union.
It's likely that a future UK-EU trade deal will be subject to approval by all EU member states and their sub-national parliaments.
Nothing less than the fate of the global economy lies in the balance as the two strong-willed leaders sit down for their first one-on-one meeting.
A new WTO trade deal is expected to provide up to $1 trillion in economic gains by eliminating bureaucracy. But that's not its most important benefit.
As the UK sets up post-Brexit trade deals with Commonwealth countries, it should be mindful of history.
Negotiating trade deals is a tremendous task and requires clarity for each and every economic sector involved. Unfortunately, the White Paper offers little detail on this.
Much of the debate around trade deals misses some of the fundamentals of what they actually are and involve.
President-elect Donald Trump has offered the UK a quick post-Brexit trade deal but he'll face some legal hurdles to make it happen.
Britain has a number of bilateral treaties with Eastern European countries that will remain after Brexit.