If, after exit, a conflict arises between two pre-exit laws, one of which is an EU-derived law and the other not, then the EU-derived law will continue to take precedence over the other pre-exit law. Any other approach would change the law and create uncertainty as to its meaning. This approach will give coherence to the statute book, while putting Parliament back in control. Once the UK has left the EU, Parliament (and, where appropriate, the devolved legislatures) will be able to change these laws wherever it is considered desirable.

High

https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/604516/Great_repeal_bill_white_paper_accessible.pdf

Chapter 2, Paragraph 2.20