The one-year limitation rule has since been changed.
Gray is appealing his convictions and had applied to the Court of Appeal to access microscope slides and blocks taken from the baby's brain during the post-mortem examination.
His lawyer Anselm Williams told a hearing in June that an overseas expert, Dr Daniel du Plessis in the UK, said he needed the slides before being able to give an opinion on the merits of the appeal.
The court heard that the slides are in the custody of the forensic pathologist who did the post-mortem examination, Dr Martin Sage.
Sage expressed various concerns about releasing the slides, especially when the post-mortem examination report was not part of the evidence at trial, and that the coronial process has not yet been completed.
He also had concerns around his obligations and professional responsibilities to the coroner and the baby's family as the effective custodian of the slides.
The forensic pathologist required a court order before releasing the material.
But in a newly released decision, the Court of the Appeal has ordered Sage to provide the UK expert du Plessis with the microscope slides and blocks, along with macroscopic photographs taken during Carter's post-mortem examination "relating to the dissection of the brain".
The court explained that all but one of the concerns raised by Sage had been "largely resolved", including revelations that the coronial inquiry into the baby's death, while remaining open, has been adjourned until the end of criminal proceedings, including any appeals.
"We note too that the appellant [Gray] and Dr du Plessis are willing to comply with any conditions imposed on the handling of the slides and blocks and meet the reasonable costs associated with that," the Court of Appeal has ruled.
The victim's family doesn't oppose the slides being sent to the overseas expert "provided they are returned so they can at the appropriate time be buried with the baby".
The court was also satisfied that du Plessis, a consultant neuropathologist who is employed by an NHS Trust in the UK and who also runs a private independent forensic practice, has the necessary expertise to do the work.
But Sage was "a little puzzled" that there was no concurrent request for him to supply his report or any of the macroscopic photos relating to the dissection of the brain.
Sage struggled to see how by solely examining the microscope slides from a case in which the alleged assault occurred more than 12 months before the death, any pathologist could provide fully informed probative information that might contribute to the appeal.
He also questioned whether the material sought was relevant.
"However, in our assessment, while that view must be and is noted, it cannot prevail for the purposes of disclosure where there is a competing view from another expert," the Court of Appeal concluded.
"This is not a case of a disclosure application that is speculative or unsupported.
"We have therefore decided it is in the interests of justice to make an order for disclosure of the microscope slides and blocks and the macroscopic photographs in the custody of Dr Sage."
