Wales will become the first country in the United Kingdom to adopt an organ and tissue donation scheme based on presumed consent after assembly members voted in favour of a bill on Tuesday.
The opt-in system currently in place across the UK relies on people signing up to a voluntary scheme and carrying a donor card.
But the Welsh government wants to introduce a system in which individuals will be presumed to have consented after death unless they specifically object during their lifetime.
Members of the Welsh Assembly in Cardiff voted 43 to eight in favour of the scheme, which is on course to come into force by 2015.
The Human Transplantation (Wales) Bill aims to increase the number of organs and tissues available for transplant by introducing the so-called "soft opt-out" system.
Donation rates could increase by between 25 and 30 percent under such a system, says the government.
Richard Lewis, the British Medical Association's secretary in Wales, called the Bill "the most important piece of legislation created in Wales since the (medieval manuscript) laws of Hywel Dda.
The assocation was delighted that the Welsh National Assemby was showing the rest of Britain the way forward, he added.
"Patients across the country will now benefit directly or indirectly from this Bill."
But Clwyd West representative Darren Millar called for an independent evaluation of the scheme, warning of "unintended consequences".
"I'm opposed in principle to a system where organ transplantation becomes a passive act, and consent for it is presumed, or as the Bill puts it deemed, by the state," he said.
The new scheme offers three options: a person will be able to register to explicitly opt in to the new organ donation scheme or opt out of it. Where a person fails to express a preference he or she will be deemed to have given consent by taking no action.
Relatives will still be able to object to their family member's organs being donated.
Campaign charity the Kidney Wales Foundation (KWF) has hailed the new scheme saying it will increase the number of vital transplant donors.
"This consent law has had a positive and sizeable effect on organ donation rates of some 25 percent to 35 percent higher on average in deemed consent countries," said Roy Thomas, chief executive of the KWF.
"Currently only around a third of the Welsh population is on the organ donor register and this is around the same for the UK as a whole."