The decomposition meant that pathologists were unable to rule out third party involvement as a cause of death.
Emily Whelan, 25, was found unresponsive in her bedroom in Yeadon in November 2016.
She was rushed by ambulance to Leeds General Infirmary but sadly died in hospital a day later on November 8.
An initial cause of death was given as a hypoxic-ischaemic brain injury after a cardiac arrest.
Despite the cause of death given, the family suspected Emily may have been killed and a pathologist examined her body.
However, third party involvement was unable to be ruled out because of decomposition to her body.
Her body had been stored in the mortuary at the LGI until December 23, 2016.
It was transferred to the Bradford mortuary.
A court hearing held in 2020 revealed how her body had only been stored in a fridge, rather than the standard procedure of freezing the body.
The case was brought by six of Emily’s family members, led by her mother, Caramella Brennan.
Leeds NHS Hospital Trust denied liability, which resulted in the court case.
In a judgement released on Friday, Judge Andrew Saffman concluded that Leeds Teaching Hospitals NHS trust had breached human rights laws by failing to preserve Emily Whelan’s body.
The family were awarded damages following the ruling.
Leeds Hospitals NHS Trust apologised to the family for the distress caused and said their "high standards" had not been met on this occasion.
The court determined that a hospital has a 'legal obligation to treat a body with dignity and respect' to ensure it does not badly decompose to prevent a breach of Article 8* of the European Convention of Human Rights.
The court had heard evidence that Emily's body was so badly decomposed it was unrecognisable.
Following the case, Emily's mum Caramella Brennan said the family's conviction in holding the hospital to account had been "vindicated" by the ruling.
She said: "Emily’s family was devastated after we were informed that her body had only been refrigerated and not frozen by the Leeds General Infirmary after her death.
"We were told not to view her body because she had so badly decomposed we would not recognise her.
"The Leeds NHS Trust has failed to accept any responsibility for its role in this terrible incident and the impact it has had on us.
"The Trust has fought the family right through the case.
"The family’s conviction in wanting to hold the hospital to account for its unacceptable conduct has been vindicated by the Court.
"We could not have done more to respect our memories of Emily and the role she played in all our lives."
The family was represented by Mr Matthew Gold of Matthew Gold, solicitors and Nick Brown was the instructed barrister.
Solicitor Mr Gold said "to permit a body to so badly decompose that it becomes unrecognisable is not just morally repugnant it is now unlawful".
He added: "The Human Rights Act continues to assist the victims of injustice to hold public authorities and their employees to account for conduct with devastating consequences.
"The Court decided, in a detailed and balanced judgement that there is now a legal obligation on mortuaries to properly preserve bodies to ensure they are given dignity and respect after death.
"The family’s long and hard fight against the Leeds NHS Trust has been vindicated and will hopefully, as the judgment points out, result in mortuaries improving their practices to ensure that this does not happen again."
Dr Phil Wood, Chief Medical Officer at Leeds Teaching Hospitals NHS Trust, said: “It is important to us that we treat all of our patients who have sadly died in our care with the utmost respect and dignity.
"We are very sorry that our high standards have not been met on this occasion and we apologise unreservedly to Emily’s family for this and the resulting distress it has caused.
“We have protocols in place to ensure safe storage of bodies in our mortuary, so that we fully meet national Human Tissue Authority (HTA) guidance.
"We have continued to regularly review these protocols and train our staff so that our processes are robust and followed correctly.”
Support the YEP and become a subscriber today. Enjoy unlimited access to local news and the latest on Leeds United, With a digital subscription, you see fewer ads, enjoy faster load times, and get access to exclusive newsletters and content. Click here to subscribe.