Who you let into your country is a fundamental power of a sovereign people and government. Making decisions about who can come and who can work is best done fairly, with the same criteria for people from anywhere in the world. Membership of the EU prevents a country exercising that right, or being fair to applicants.
Deciding how much money to raise in taxes and how much to give out in welfare benefits is also a fundamental power of a sovereign people and Parliament. When Mr Blair pushed us into the Nice and Amsterdam Treaties, and Mr Brown finished the job with the Lisbon Treaty, they assured us that tax and welfare were “red line” issues. The Uk would still be free to make its own decisions about how much to tax, and how much to give to whom in welfare. They misled us.
As a result of the centralising Treaties we are signed up to, the UK now has to accept any migrant from the rest of the EU and has to accept substantial intervention in our tax and welfare policies. The government understands the unpopularity of the EU controls on these matters, and has said it wishes to renegotiate our relationship.
In the letter to Donald Tusk they sought to tackle the welfare issue, and argued that if they stopped benefits to people arriving from the rest of the EU for a four year period after their arrival they would also tackle the questions of the numbers of migrants. These two problems are different. There is some overlap, but a sovereign country needs both to control its own borders,and settle its own welfare. The proposal in the letter to Mr Tusk does not give us control back over our borders. Nor would it even necessarily give us control back over welfare. Unless we have a Treaty change which explicitly says the UK can choose any welfare system it likes, a future EU or ECJ decision could damage or get round any agreement to let us stop benefits to EU arrivals for the first four years.
Mr Johnson says maybe the UK could get an opt out from the freedom of movement requirements. That seems very unlikely, given the strength of feeling on the continent about the importance of freedom of movement. Nor does it tackle the welfare issue. It would be an opt out worth having, but it would not allow us to settle our own welfare criteria.
The lack of power the UK now has over both borders and welfare is at the heart of the EU membership debate. To restore our sovereignty we need clear changes to our Treaty commitments. This does not seem likely. The simplest way to take back control is to leave the treaties altogether. Then we would have the right to set our own immigration policy and our own welfare policy, as we were told we still could when a previous government signed away our democratic powers.