when courts in the UK or the EU interpret provisions of national legislation intended to give effect to the agreements, they could take into account the relevant case law of the courts of the other party.

The agreed rule changes would also need to be given effect in UK law through domestic legislation. The UK Parliament would scrutinise this legislation in accordance with normal legislative procedure, respecting the principle that a sovereign Parliament has complete control over domestic law. This means that the UK Parliament could decide not to give effect to the change in domestic law, but this would be in the knowledge that it would breach the UK's international obligations, and the EU could raise a dispute and ultimately impose non-compliance measures.

the Joint Committee would consider whether a proposed new or amended UK rule remained equivalent with the EU’s existing rule, or an existing UK rule remained equivalent to a proposed new or amended EU rule.

There would therefore always be an option for the rule not to be added

where there is a common rulebook, these rules can be relied on by individuals and businesses and enforced by UK and EU courts in the same way, because they have been interpreted consistently;