Can you contest a Will if someone lacked mental capacity?
In this week’s episode of Brisbane’s Legal Lowdown on 4BC, Attwood Marshall Lawyers Estate Litigation Senior Associate Duncan MacDougall joins Sofie Formica to explore a topic that is sadly becoming more common in our ageing population: what happens when someone signs a Will but may not have had the mental capacity to do so?
As Australians live longer, cognitive issues like dementia are on the rise, often complicating end-of-life planning. Duncan unpacks the concept of testamentary capacity, the legal test to determine whether someone was of sound mind when they made or changed their Will.
The episode delves into:
- What mental capacity means in legal terms when creating a Will or Enduring Power of Attorney
- What evidence courts look for when a Will is challenged
- Why early legal advice and medical assessments can protect families and prevent disputes
- How DIY Wills and informal documents increase the risk of challenges, particularly when elder abuse or undue influence is involved
- Real-life examples of Wills overturned due to lack of capacity
Duncan emphasises that it’s not just about having a diagnosis of dementia, capacity can fluctuate, making timing and documentation critical. He urges families to get a baseline assessment and prepare estate planning documents early, reviewing them regularly as circumstances change.
Whether you’re supporting an elderly loved one or managing your own affairs, this episode highlights the importance of taking proactive legal steps to safeguard your wishes and avoid family conflict down the track.
Sofie: It is that time of the week, Brisbane’s legal lowdown now with Attwood Marshall Lawyers. Today we’re unpacking a sensitive but a really important question, and one that it will be too familiar to too many of you listening this afternoon.
We know that people are living longer. We also know that when it comes to those who are getting older and more often than not, we’re also dealing with issues of mental capacity.
So, how can you, and can you, contest a will if someone makes it, and you perceive them to have not had full mental capacity at that time. It’s something that comes up more than you think. As I said, we know that our loved ones, our aged in the family can sometimes be facing health challenges like dementia.
So, what exactly does it mean to have capacity when you’re signing a will? And who decides when someone doesn’t have it?
Joining us now to navigate those questions, Attwood Marshall Lawyers Estate Litigation Senior Associate, Duncan MacDougall. Good afternoon to you.
Duncan: Hi there Sofie. Thanks for having me.
Sofie: As always, while we are talking this afternoon with Duncan, if you have a question you’d like to send through to us via text 0499 880 882 or if you’d like to speak to us, you can call 133 882.
Can we start with that big question, though today, Duncan, can someone contest a will if they believe the person who made it didn’t have the mental capacity at the time to do so?
Duncan: In short, yes, they can. It’s becoming one of the biggest challenges these days as our population ages. If someone did lack the mental capacity to make a valid will, the law says that will can be set aside. That means that will had no legal effect and an earlier valid will will then take effect, or if there was no earlier will intestacy rules, in which case it’s down to a legislative list of people who can benefit under legislation.
Sofie: And I’ve heard when people talk about this, the concept of testamentary capacity. What does that mean?
Duncan: Yeah. So, it’s a very specific legal test when it comes to testamentary capacity. It’s really the capacity somebody has in order to prepare a will. There’s a number of things that they have to satisfy being they have to understand the nature and effect of making a will, generally know what assets they have, what liabilities they have, who can make a claim on their estate, like family, dependents, those in a close relationship with, and be free of any delusion or disorder that might affect how they might distribute their estate.
And that goes separately, if it’s an enduring power of attorney, that goes even a step further in relation to the delegation of decision-making power whilst they’re alive.
Sofie: And that was what I was going to ask you. We talk about making a will or having an enduring power of attorney. So what does the law require someone to in coming up with those sort of two different things?
Duncan: Yeah. So, with a power of attorney, it’s very similar type of circumstances there, but it’s really going that extra step saying, listen, I understand the powers I’m giving these people to take care of my finances and my personal and health affairs should I lose capacity.
With the will, it’s really understanding who’s benefiting what, and knowing the consequences of doing certain things via your will.
Sofie: And I think that there’ll be this understanding that it’s one thing to have had a diagnosis from a doctor, it’s something completely different when people might be before that stage, when as family, you may think that something’s not quite right, but you don’t necessarily have a diagnosis that you can go on that’s come from a health professional. Is that a bit of a grey area?
Duncan: Yeah, it’s a big grey area and normally these kind of challenges arise, it happens when wills are changed later in life, particularly when somebody’s already experiencing cognitive decline or showing those signs of confusion.
Sofie: Does it mean that you need to make sure that these things are done a, in advance, or b, if it needs to be changed after the fact, is there a process that you should go through?
Duncan: Yeah. So, it’s a telltale sign to get your affairs done earlier and before you start experiencing any sort of cognitive decline. It’s really a joint effort between the solicitor who you’re seeing to assess capacity or take a bit of an assessment of their client’s capacity, but also if there’s any confusion or grey area there, they’ll take a step further and engage the client’s GP or geriatrician to then get a report to use as evidence down the track if it’s later challenged.
Sofie: Ultimately, who decides if someone’s lacked capacity? The doctor, a lawyer, or both? And particularly in a case and I wonder whether or not you can speak of an example where someone may have passed and it’s the time to actually enact what the wishes were, and that’s when the question of capacity is being asked?
Duncan: It really comes down to a team effort. I tell people, even when clients come in and they get a bit standoffish saying, well, I’ve got capacity, I’ve got my marbles, why are you challenging me on my capacity? I say the more evidence we’ve gotten now if it is later challenged, it can be used as safeguards to protect your will and uphold the integrity of your will down the track. Now it’s ultimately a judge who decides whether or not the person had capacity based on all the evidence available. So, down the track if a diagnosis of dementia shows up on a death certificate, if there’s really challenges as the capacity, those things happen. And an example where that took place is, for example, somebody was kind of in that grey area with moderate to severe dementia, signed all and all of their assets to one child over the others, it was later found out that they did not have capacity at the time to make their will and really there was not enough notes there and very unprofessional notes from the solicitor who prepared the will and not enough medical evidence or sorry, there was more medical evidence to outweigh the fact that there was a medical decline there or sorry, a cognitive decline.
Sofie: What kind of medical evidence or documentation would a court be looking for if they were trying to prove a lack of capacity?
Duncan: It’s really those medical records from around the time the will was made, especially notes from GP’s, specialists, hospitals, statements of people who knew the person, so family, friends, carers, nurses, evidence from the drafting solicitor, so their will file might even come into question down the track.
Or even a retrospective capacity opinion from a medical expert down the track, who reviews all the records and gives an opinion on whether that person likely met that legal test that we were talking about earlier.
Sofie: If you’ve just joined us this afternoon, we have Attwood Marshall Lawyers for estate litigation, Senior Associate Duncan MacDougall just talking through a really sensitive I think but important concept which is capacity when it comes to the time of will making. And I just wonder whether or not you could share maybe a real-life experience with us, Duncan, where a will was successfully overturned, like you just talked about there when it came to capacity concerns, but after the time that the person had passed.
Duncan: So, in that example, I was speaking of earlier, although the will was properly signed, medical records showed confusion, memory loss and impaired reasoning.
Sofie: Without a diagnosis, though, or with a diagnosis?
Duncan: Well, at that point, the one I’m referring to, there was a diagnosis of dementia, but there may be instances where it’s bit of on the edge because some people with the, even those early stages of dementia may in times have capacity and that’s really the grey area that that causes most of these issues, is that one day they’re good and another day they don’t know who they’re talking to.
Sofie: There’ll be issues with families where maybe, you know, one sibling is trying to sort of force the hand a little bit to either have things put in place or changed. What can families do if they’re finding that they’re not on the same page with how to move forward?
Duncan: Yeah. And that’s an area I see quite regularly as well, especially with the elder abuse cases that are starting to arise. They take it to their advantage. They say, well, mum or dad is starting to lose their marbles. I’m going to take advantage of this. Either convince them to change their will. And a lot of these things happen when wills are not prepared by solicitors.
So, all these DIY wheel kits, things like that. When really the lawyers not there to ask the right questions and get that that those medical reports if needed. They’re not there to act as a key witness. It’s when people try to do their estate planning themselves again, it’s going to be harder for them to uphold that will down the track if it’s later challenged.
But again, at the end of the day, get that advice early. Get those medical assessments early and avoid those informal wills.
Sofie: It’s so hard to know because what is early? We’re living longer than we ever have before. Things are more complicated than they’ve ever been. And I think the most important way to end our conversation today is to really give some advice for anyone with a loved one who might be experiencing particularly early stage dementia or some sort of cognitive decline to give them what you would suggest be the proactive steps that they could be taking so that they can protect their legal rights and I think more over avoid there being disputes later.
Duncan: That’s right. And get a baseline, you know, start to start to engage, get a will prepared. It’s something that you review every two to three years. It’s not something you put in place, and it remains stagnant over 10 years 20 years you never review it again.
As your circumstances change as you age, as your personal and financial circumstances change, their family dynamics change, those are all key indications to then we visit that to make sure those safeguards are in order.
Sofie: Not to mention that somebody could win this house and then they’ve got another asset that they need to make sure is protected in their will for what they want to have happen to it as well.
Duncan: Exactly. We all want that.
Sofie: Absolutely. What a wonderful problem to have. Thank you, as always for your time for answering those questions for us and for knowing that you are there if there are listeners who would like to reach out for more information. That is Attwood Marshall Lawyers Estate Litigation Senior Associate Duncan MacDougall. We’ll talk again next week.
Duncan: Thanks for having me again.

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