The RCMP say the document is based on a statement Gerald Barton gave to a senior Mountie investigating an alleged case of rape in Jordantown, N.S.
In the statement, Barton is quoted as saying he had consensual sex with a 14-year-old girl, who later gave birth to a boy.
It was used to convict Barton, then 19, of having sex with a female between the ages of 14 and 16. He was sentenced to a year of probation.
Barton's lawyer, Dale Dunlop, told the Nova Scotia Supreme Court that his client was the victim of a negligent investigation by the RCMP, alleging the statement was either fabricated or the result of subtle coercion.
Earlier this week, Barton testified that he never spoke to police and didn't plead guilty to the crime. He said the sexually explicit terms in the statement were words he wouldn't have understood at the time.
In his closing argument, Dunlop said the lead RCMP investigator, corporal Earl Hamilton, could have manufactured the statement, or he could have encouraged Barton to say he had consensual sex with the girl to wrap up the case and spare the accused from facing a more serious rape charge.
"The only conclusion you can come to is that this statement wasn't taken properly," Dunlop told Justice James Chipman, who reserved judgment and is taking written submissions on a charter argument in the case on April 25.
Barton's conviction was quashed by the Nova Scotia Court of Appeal in 2011 after the complainant recanted her story and DNA testing proved Barton wasn't the father of her son. The genetic tests said the brother of Barton's accuser was the father of the child.
Earlier Thursday, federal lawyer Angela Green said Dunlop failed to prove his case, saying there was no evidence to suggest Hamilton was careless in his work or that he fabricated the incriminating statement.
However, Chipman challenged that assertion, suggesting Hamilton may have been eager to close the file and clear up a scandal in the community.
Green rejected that argument.
"There's a common-sense disconnect on why the police would fabricate a statement on a lesser charge and then hand it to the Crown," she said.
Before closing arguments began, Dunlop withdrew Barton's claim of malicious prosecution against the provincial attorney general, saying it's clear that the Crown attorney in the case could only act on the statements given to him by the RCMP.
On Wednesday, former Crown attorney Charles Haliburton testified that Barton had pleaded guilty to the charge just as his trial was about to begin on Jan. 14, 1970.
Haliburton said he decided to charge Barton with having sex with a minor, even though the complainant's statement to police indicated that she had been violently raped, because he had "a real prospect of conviction" on statutory rape.
"It's the one that (Barton) admitted to" in his statement to police, he said Wednesday.
Dunlop said Barton is seeking compensation in the $500,000 range and an apology.
Barton said an apology now is a waste of time.
"For them to come after all this time and apologize to me, what's it going to change? It ain't going to change what they done to me for 40-some years."