Peers are debating former Labour Lord Chancellor Lord Falconer's assisted dying bill.
The Bill proposes allowing doctors to give a lethal dose to terminally ill patients judged to have less than six months to live.
A survey conducted for ITV's Tonight programme found 70% would support allowing assisted dying under the framework outlined by the Assisted Dying Bill.
Desmond Tutu has become the latest high-profile figure to come out in favour of a change in the law on the right-to-die.
Writing in the Observer, the former Anglican bishop said he reveres "the sanctity of life - but not at any cost."
His comments come after the former Archbishop of Canterbury Lord Carey said the case of locked-in sufferer Tony Nicklinson inspired him to change his mind on the issue.
A Bill to legalise assisted dying will be debated in the House of Lords next week.
Ahead of tomorrow's Lords debate on assisted peers, Tonight speaks to those arguing passionately for and against the Bill.
Chris Woodhead, the ex-Ofsted chief who suffers from motor neurone disease, has made an emotional call for assisted dying to be legalised.
Lord Falconer insists his Bill will provide clarity to fix Britain's "broken" laws around assisted death whilst protecting the vulnerable.