Davison is the president of the World Federation of Right to Die Societies, which supports euthanasia and assisted suicide for adults with incurable illnesses. The New Zealand End of Life Choice Society (formerly the Voluntary Euthanasia Society) is a member.
At a speech at the federation's conference in 2014, the 57-year-old said "not all quadriplegics want to die, but those who do want to, should have the option".
The executive officer of Euthanasia-Free NZ, Renée Joubert, said Davison's actions suggested the federation wants any adult to be eligible.
"Mr Davison's words and actions demonstrate that 'assisted dying' advocates don't really want a narrow law limited to terminal illness, but one that would eventually allow virtually any competent adult to be eligible, including people with disabilities.
"Disabled people would be included under both clauses of David Seymour's Bill.
"Terminal illness involves disability. So do many other long-standing physical and mental conditions."