Terminally Ill Adults (End of Life) Bill

Baroness Cass Excerpts

Friday 5th December 2025 Lords Chamber

[Baroness Cass (CB)]

My Lords, as Sarah-Jayne Blakemore has been widely referred to, it might be useful to directly quote her. She said:

“Most of these age cutoffs have not been based on what we know about brain development, because they were decided way before we knew anything about how the brain develops during adolescence. So what I would say is that those kinds of decisions about age cutoffs”—


she is referring to the various age cut-offs for drinking, marriage and so on—

“should incorporate the new knowledge about brain development during adolescence. On the other hand, this is a question I’m asked often, I don’t think the neuroscience can provide an age for you. We can’t say, ‘Oh, the neuroscience shows that the brain becomes adult at age 18 or 24’ or whatever it might be. It’s much more complex than that”.

She goes on to describe how different brain regions develop and mature at different rates, and to talk about the individual differences in the speed of brain development:

“So what I would say is that what we know from neuroscience is the kind of age range, the very broad age range when the brain becomes mature and adult. And that’s much later than 18, between 20s and 30s for most people. So of course that cannot generate an age at which you become legally adult”.

That is what Sarah-Jayne Blakemore has said. On that basis, I support the suggestion from the noble Baroness, Lady Finlay, that, between the ages of 18 and 25, there should be enhanced and careful assessment, taking account of that perspective.

[Lord Falconer of Thoroton (Lab)]

I apologise for interrupting at this stage. This has been a very good debate, and it might be helpful if I indicate what my position in relation to this is. The thinking behind 18 is that that is the age at which you can make your own decisions about medical care. If you are suffering from a terminal illness, you can decide at 18 whether you want to withdraw treatment, for example, or what the treatment should be.

In answer to the noble Baroness, Lady Berridge, we were aware of the different views about when your brain and maturity develop, and what the noble Baroness, Lady Cass, said is absolutely correct—she read Sarah-Jayne Blakemore’s view—in that these age cut-offs that the law imposes generally are not based upon a close study of neurology; they are the law’s attempt to reflect maturity. I am indeed very aware of the fact that if you are 18, you may be more emotionally impulsive and more easily influenced than somebody of 25, 24 or 23. Equally, anybody who has had contact with people who are young and terminally ill will have found that some 18 year-olds are incredibly thoughtful and mature and some are not, for obvious reasons.

I am very influenced by the fact that I have been listening to people expressing real concern about this issue in this House. I still think 18 is probably the right age, but I am very influenced by what the noble Baronesses, Lady Finlay and Lady Cass, have said: that maybe the answer is some assurance that there is a more intense assessment for people aged between 18 and 25. The Bill says that you can have an assisted death only if you have

“a clear, settled and informed wish to end”

your life, and it is being done voluntarily. How can we be sure about those aged between 18 and 25? Two doctors and a panel have to make the decision, but some additional thing might be required.

We are slightly going around in circles again and repeating ourselves, so I suggest that I talk in particular to the noble Baronesses, Lady Cass and Lady Finlay, and that we come back on Report and see whether we need a more thorough assessment for people aged between 18 and 25—although I am not saying I am going to change the age of 18. That is broadly my position.