A rape trial was delayed for more than six months after Crown Prosecution Service (CPS) lawyers demanded access to the victim's school and social service records.
Merseyside Police had asked the CPS to approve charges against ocean sciences student Luke Hudson, 21, who was later convicted of raping the unconscious woman at a drunken house party in December 2017.
The analysis of the victim's records proved irrelevant to the case.
Hudson, of Alderson Avenue, Wavertree, was caught out when concerned friends placed a mobile phone under the door of his locked bedroom and saw him appearing to have sex with the woman while she was motionless.
When they tried to force the door Hudson, naked from the waist down, opened it and they saw the victim covered in vomit and seemingly asleep on the bed.
Hudson denied the two had penetrative sex but traces of her DNA were found on his body.
During his trial, Judge Louise Brandon expressed concerned about the length of time between the attack and charges being laid, and asked for a chronology of the case to be compiled.
After Hudson was sentenced to four-and-a-half years in prison, prosecuting counsel Ben Jones indicated a timeline had been prepared.
He said: "After medical reports had been completed Merseyside Police indicated that charges were ready in June 2018.
"However there was then a dispute between the police and CPS over access to the complainant's school and social service information."
Mr Jones said the police suggested the CPS request was "speculative," but the wrangle lasted for around six months.
Judge Brandon said the parties should "reflect" on the process.
Hudson was ordered to sign the sex offenders' register indefinitely.
The CPS said they received the file from police in September 2018, and said the case was charged in March 2019.
The service highlighted that the evidence collected in the complex investigation secured a conviction.
Deputy chief crown prosecutor for CPS Mersey-Cheshire Aksha Shahid said: "The CPS received this case from Merseyside Police in September 2018.
"A review of the material that had been collated during the investigation was carried out and further lines of enquiry were identified.
"The Police did not decline to pursue these lines of enquiry and they were carried out. The case was then further reviewed and charge was authorised in March 2019.
"This was an extremely complex and sensitive case in which the defendant exploited the vulnerability of the victim at a time and a place when she was entitled to feel safe.
"Justice was secured for this victim and a rapist was convicted because of the effective teamwork of the CPS, the Police, Counsel and the forensic expert.
"The defendant was convicted of rape on December 2, 2019, and sentenced to four years six months imprisonment and he has been entered onto the sex offenders register."
In September, the annual Violence Against Women and Girls (VAWG) report from (CPS) showed the number of rape prosecutions in the region fell from 202 in 2017-18 to 119 in 2018-19.
Across England and Wales, there were just 1,925 convictions for rape or an alternative lesser offence during the financial year 2018-19, down from 2,635 in the previous 12 months - a drop of 26.9%.
This is despite the number of rape claims dealt with annually by police forces in England and Wales rising from 35,847 to 57,882 during the last four years.
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The drop in prosecutions led campaigners to argue that rape is becoming "effectively decriminalised."
A coalition of women's organisations, represented by the Centre for Women's Justice (CWJ), is preparing to launch a judicial review case against the CPS over claims cases are being "dropped" without good reason.
But the CPS said the drop in rape charges was due to "a number of factors", including a reduction in the number of referrals from the police to the CPS, and an increase in the volume of time-consuming digital data.