Staffordshire bull terrier Butch was labelled "dangerous" by Merseyside Police after he was found eating the corpse in 2015.
Officers said the 10-year-old dog, who had been trapped in the Liverpool flat for several days, presented a danger.
But a dog charity said Butch "did what was natural" and should be rehomed.
Judge Nigel Bird has now ordered a review of the seizure order and fairness of the court hearing.
The precise cause of Butch's owner's death remains unknown.
The force assessed whether the animal, which is not a banned breed, presented a danger to others and concluded it did.
A judge sitting at Liverpool Magistrates' Court agreed and ordered the dog's destruction in April 2016.
But the Senior Staffy Club said Butch was a "friendly dog" and sought permission for a judicial review at Manchester Civil Justice Centre earlier.
The charity said Butch's owner, who had been ill for some time, had been in the process of signing him over to the charity when he died.
Spokeswoman Kate Lee said a volunteer went to collect the dog from the property but did not get an answer.
She said it was distressing and unfortunate but Butch had done "what was natural for a dog" left without water or food for a number of days.
Ms Lee said: "We were there; we were ready to take the dog from the police and take him in our kennels and assess him and find him a suitable home.
"That's what should have happened."
The dog has been in police kennels since the owner's death in September 2015.
Merseyside Police said the Chief Constable has noted the court's decision.
A date for the review is yet to be set.
A dog sentenced to death after eating his owner's body has been given a stay of execution after a judge granted a judicial review.