Valery Fabrikant, 74, serving a life sentence for murder in Quebec's Archambault Institution, had argued he needed the extra clothing because of his age and heart condition but a Federal Court judge slapped down his arguments in December.
In an interim decision, the Federal Court of Appeal ordered Correctional Service of Canada to provide him with a second parka "suitable for wearing outdoors."
The government had provided no evidence that giving Fabrikant an extra parka would be "unduly expensive, difficult or disruptive to discipline within the institution" or cause hardship to Correctional Service of Canada, Judge Karen Sharlow wrote in her order.
Sharlow also ordered the government to pay Fabrikant's legal costs.
The two sides subsequently reached an out-of-court settlement, with the warden at Archambault, Julie Cobb, agreeing to a "permanent authorization" for correctional authorities to provide the extra parka, according to settlement documents.
In response, Fabrikant agreed to give up pursuing the court case and several institutional grievances he had filed over the clothing.
Correctional authorities had rejected his initial grievance for a parka based on "regional procedure 885 of the Quebec region,'' which stipulates one parka for each inmate every three years.
The government also agreed to give him $50 to cover his out-of-pocket legal expenses as part of the settlement reached in late February, according to the documents.
Fabrikant was an associate professor of mechanical engineering at Concordia University known for disruptive behaviour against students, staff members and other academics.
He was facing dismissal when, in August 1992, he went into the engineering department with guns and ammunition in his briefcase and opened fire. He killed four academics and wounded a secretary.
Fabrikant has a long history of going to court for various issues and has been declared a "vexatious litigant," meaning he needs permission before filing further lawsuits.
Among his lawsuits was one in which he claimed his former Concordia colleagues had stolen his work — a case he ultimately lost when the Supreme Court of Canada refused to hear the case.
There was no word on how much the government spent defending its decision to deny him the parka.