OTTAWA—The Supreme Court of Canada is expected to deliver a ruling today on whether a Canadian fashion mogul who faces sex trafficking and racketeering charges in the United States will stay behind bars. Peter Nygard applied earlier this year to the country’s highest court for permission to challenge a Manitoba ruling that denied him bail. An Appeal Court justice ruled that Nygard’s detention was necessary because of the enormity of the allegations against him. Nygard is accused by American authorities of using his influence to lure women and girls with the promise of modelling and other financial opportunities. He has denied all the allegations. Nygard’s lawyers have argued that there is inconsistency in how courts decide on incarceration when it comes to extradition hearings. Nygard was arrested in Winnipeg last December under the Extradition Act and faces nine counts in the Southern District of New York. The 80-year-old was first …