In areas where the UK had committed to maintain a common rulebook with the EU, the Joint Committee would need to agree on whether a proposed EU rule change should be incorporated into the agreements, and there would be a process for the UK Parliament to be consulted on this. If the UK and the EU could not agree, the Joint Committee should consider all other possibilities and endeavour to maintain the functioning of the relevant agreement, including the possibility to recognise the equivalence of legislation. If this was not possible after a defined period and an imbalance was created, proportionate and where possible localised rebalancing measures could be proposed, for instance, requesting financial compensation. Where there was no agreement over these measures, or they were not possible, the relevant part of the future relationship could be suspended
In areas where there is a common rulebook, there could be proportionate implications for the operation of the future relationship from the decisions taken by Parliament about what legislation it chooses to adopt in the future. For instance, if the UK and the EU had agreed to add a rule change to the agreements, and if the UK Parliament decided not to give effect to this change in domestic law, it would be in the knowledge that it would breach the UK's international obligations, and that the EU could raise a dispute and ultimately impose non-compliance measures on the UK. As set out in the White Paper, the type of measures that could be imposed for different sorts of breaches would be technical, but could include financial penalties or suspension of specific obligations.