Currently in the UK we have voluntary self regulation for complementary therapies i.e. it is not compulsory. It is the person doing the Reiki who is regulated, not the Reiki itself, i.e. it is how they work and their interaction with the public.
The Regulator regulates the practice of Reiki (and other therapies/disciplines), primarily to protect the public. There are currently two Regulatory Bodies soliciting membership by practitioners or Reiki and other complementary therapies in the UK.
In order for Regulation to be effective and representative of the discipline being regulated, there were many stakeholders and advisers who were consulted during the regulatory process, and who will continue to be involved.