It’s a cold November evening, and MPs are no doubt snuggled up wondering what to watch on TV and how to vote on Kim Leadbeater’s assisted dying bill. What a perfect opportunity to watch my documentary on that very theme, Better Off Dead?.

You may know me or you may not. I’m the wheelchair-using disabled woman who spent eight years playing the forensic boffin Clarissa in the BBC drama Silent Witness. I’m also a disability rights activist, and when it comes to assisted suicide (as I prefer to call it) I’m a bit of a nerd. Oh yes, and I’m opposed to a change in the law: I don’t think we should allow medical professionals to assist some people to end their lives.

Because those in favour of it like to discredit any opposition as anachronistic and arising from faith, I feel obliged at this point to tell you that I am not religious. Instead, I oppose the bill from a secular social-justice perspective. I should also state for the record that opposing assisted suicide does not make me cruel, evil or lacking in compassion – although I’m regularly called these things by proponents.

As someone who relies on the health service and the state for my survival, I simply have a healthy distrust of giving either of them any more power over my life – and death – than they already have. Though some people want the right to die, many of us are still fighting for the right to exist. That’s why I’m part of Not Dead Yet, an international network of disabled people who oppose a law that would give the state and the medical profession potentially even more involvement in many ill and disabled people’s lives.

While I was making the documentary, a disabled friend had a serious but completely treatable condition yet was placed in a frailty ward – a place for older people (and my friend) where the support provided was more about cups of teas than CAT scans, and where, on one night, none of the staff were qualified to provide her with a cannula for pain relief as she screamed in agony. It was “lucky” that she had a life-threatening seizure that put her in intensive care, because that’s when the medical staff began to provide active care. But still she woke to find “Do not resuscitate” (DNR) written on her notes without her consent. It was a tough time.

A month later, another of my closest friends, who is also a disabled person, had a similar adventure. The district nurses who visited him day after day failed to notice the delirium that sepsis had caused until he was rushed into hospital with near-total organ failure. And there, despite his fervent opposition to a DNR, there was one on his notes, too. His partner and brother, my partner and I and a palliative care consultant I know from this campaign worked through the night to have this removed. The next day in a “the end is nigh” conference with his doctors, they were shocked to hear that this 58-year-old disabled man in a wheelchair had any kind of life – any kind of quality of life.

Both of these friends will be joining the rest of us who are passionately protesting against assisted suicide outside the Houses of Parliament tomorrow. We’ll be there because we fear that this law will further enshrine these misconceptions, underestimations and stereotypes – and the inherent inequality that exists for ill, older and disabled people. There are too many anecdotes about disabled people having to fight the insidious, unconscious bias that says people who have certain conditions, look a certain way or need care or support might just be better off dead. And we remember the early days of Covid when the death tolls rose, with the reassurance from behind the podium that those dying were only people with “underlying health conditions”. As someone who fitted that definition, I was so frightened at seeing myself as a statistic every single day that I resorted to my survival mode of humour and tweetedthat I might as well change my name to Underlying Health Condition, just to cut out the middle man. In case you’re wondering, I never did.

During that time, many of us feared that if we ended up in hospital we wouldn’t stand a chance of ever leaving. They were dark times for everyone and difficult choices were being made in impossible circumstances. Decisions over who should get the bed or the ventilator or the resources, however, felt very personal: “frailty scores” meant those of us who needed help with basic daily tasks were, even briefly, placed lower down the list of priorities. Infected people were moved into residential care homes with older, frailer residents. Letters went out to similar homes including those for people with learning difficulties to suggest “blanket” DNR orders. If we learned anything from the Covid-19 pandemic – so far – it is perhaps that some people’s lives aren’t valued as much as others.

Leadbeater has repeatedly suggested that we need to put our faith in medical professionals, lawyers and judges. But many doctors and judges admit they are fallible. My experiences and those of many other disabled people, also show this is true. And faith in our current broken systems and the people trying their best within them doesn’t feel like a gold-standard safeguard to me.

As long as the lives of marginalised people are seen as more disposable than others, how can any safeguards truly protect us from the potential abuses, coercion and mistakes that will come if assisted suicide is legalised?

That’s why I made the documentary. And that’s why I urge MPs to watch Better Off Dead? before this life-and-death vote.

• Liz Carr is an actor and disability rights activist