This article contains spoilers.

The most shocking moments of the true crime documentary Making a Murderer don’t involve its convicted-exonerated-convicted-again protagonist Steven Avery. They depict two police officers gently coaxing a softly spoken teenager to recount his role in a vicious crime.

Viewers of the wildly popular Netflix series know the story: Steven Avery is released from prison after serving 18 years for a rape he didn’t commit, only to find himself back behind bars for the brutal murder of photographer Teresa Halbach. A cornerstone of the prosecution’s case against Avery is the confession of his 16-year-old nephew, Brendan Dassey. The teenager is presented as an accomplice to the murder.

Dassey is described in the series as “learning disabled”, who reads at a “fourth-grade level”. He is interrogated — alone — and possibly coerced by police into confessing to rape and murder. Dassey later recants the statement, both inside and outside of the courtroom. But, ultimately, Dassey is condemned by the dubious confession and sentenced to life imprisonment for Halbach’s murder.

Dassey’s treatment should shock viewers because it shows how the system is skewed against an accused person such as Dassey. It highlights the importance of appropriate supports for people with cognitive impairments in the criminal justice system. This is as relevant in Australia as it is in the United States.

The Australian system

People with cognitive disability are over-represented in the criminal justice system. This includes people with intellectual impairments, acquired brain injuries and mental health issues. Indigenous people with cognitive disability are doubly disadvantaged.

The Sydney-based Intellectual Disability Rights Service has called for support for people with cognitive disabilities when interacting with the police. Without appropriate support, people with cognitive disability may want to please authority figures, or may not understand questions or legal cautions. They may also just want to get out of the police station as quickly as possible.

Organisations such as the Victorian Office of the Public Advocate provide “independent third persons” during police interviews for precisely these reasons. Such support might have avoided the injustice of Dassey’s case.

Disadvantage doesn’t stop at the investigation phase. Court proceedings pose a number of pitfalls for accused persons with disabilities. And it is here that Australia lags behind other jurisdictions. In the United Kingdom and Canada, defendants can be assisted by “intermediaries” who help people with disability understand proceedings and give evidence in court.

Indefinite detention

In Australia, accused persons with cognitive disabilities can be held indefinitely after being deemed unfit to stand trial. A person is deemed “unfit” if a court is satisfied that he or she cannot understand the charges, or struggles to follow court proceedings. This is perhaps understandable given the impenetrable language and alienating formality of modern judicial systems.

“Unfit” defendants are diverted out of the mainstream criminal justice system. They are never convicted of any crime. But that does not mean they walk free. They can be detained indefinitely, in mainstream prisons or secure facilities. Often, they are detained for far longer than any sentence they would have received.

Grave injustices can follow, as the recent high profile cases of Marlon Noble and Rosie Anne Fulton show. Both were found unfit to stand trial. Noble spent ten years incarcerated for a crime it now seems he didn’t commit. Fulton was detained for 22 months on relatively minor driving charges in the Northern Territory.

According to estimates by People with Disabilities Australia there are at least 100 people detained across Australia in similar circumstances; at least half are Aboriginal or Torres Strait Islander.

Numerous reviews and law-reform agencies have recommended changes to unfitness to plead laws. A recently announced Senate inquiry provides an opportunity for nationally consistent reform.

Seeking support and equality

The UN Convention on the Rights of Persons with Disabilities, which Australia has ratified, can help guide reform. The convention promotes a shift away from ideas of “vulnerability” and “specialness” towards equality and accessibility.

From this view, cases like that of Dassey, Marlon Noble and Rosie Anne Fulton are not tragedies of exploitation. They are tragedies of inaccessibility. They are failures of criminal justice systems to cater for everyone. International human rights law – and the fundamental notion of equality before the law – demands “reasonable accommodation”. This includes appropriate support for people with intellectual disability charged with a crime.

Our new research project sets out to develop such supports. Our team of researchers will partner with legal services to create and evaluate support for accused persons with cognitive disabilities at risk of being deemed unfit to stand trial. This will include a focus on support tailored to the needs of Indigenous people with cognitive disabilities.

Because – when it comes down to it – maybe all Brendan Dassey needed was someone to back him up.

Read more: Making a Murderer: why innocent people confess under interrogation