Hold a referendum to approve/disapprove any US trade agreement due to the potential threat to our sovereignty and economy from Investor-State Dispute Settlements. If our EU relationship was unwanted due to legislative 'interference' so should any US deal.
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The treaty between the UK and EU was rejected through referendum because it allegedly affected UK sovereignty.
Any US trade deal could be a much greater threat to UK sovereignty through punitive Investor-State Dispute Settlements, which clearly do impact on sovereignty and our ability to determine our own employment and safety laws and standards, along with our control of our own economy. A US deal therefore must also be subject to referendum.