The system would presume people have agreed - and is already in place in Wales.
The results of a study by Queen Mary University of London suggest family members would be more likely to veto a presumed consent.
Diane Franks told Premier what made her decide to give away one of her organs.
She explained: "A friend of mine in America donated her kidney to a stranger... and as soon as I heard of it, it just totally overtook me as something that is the most perfect gift you could give anyone - to save their life now without harming yourself."
The new system for England, which will come into effect in 2020, will mean people, apart from certain groups, will be considered organ donors unless they have explicitly recorded a wish not to be.
Many organ donor systems across the world include a clause which allows the final decision to donate to be made by family members.
And families vetoing organ donation is said to be one of the biggest barriers to donation.
The authors of the study highlight figures from NHS Blood and Transplant which show that in 2010, 500 families vetoed organ donations despite being informed that their relative was on the NHS Organ Donor Register.
This led to an estimated 1,200 people missing out on potentially life-saving transplants, they wrote.
Franks told Premier the government's proposals raised ethical questions.
"It's a difficult one because over 80 per cent of people say they would donate, but less than 40 per cent are actually registered, yet every chance is given for people to register," she said.
However, she added: "Organ donation should be a gift and I'm not quite sure how one views an opt-out as a gift if you're being told you have to donate."
Listen to Diane Franks speaking on Premier's Inspirational Breakfast to John Pantry and Rosie Wright:
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