TORONTO—The Conservative party’s use of CBC news footage in a partisan attack ad and tweets was a copyright infringement damaging to the public broadcaster’s integrity and impartiality, Federal Court heard Thursday. In submissions to the court, CBC lawyer Andrea Gonsalves said the federal Conservatives exploited the very qualities that make the CBC a trustworthy source of information. “The works in issue are the products of CBC’s skill and judgment; they reflect its high journalistic standards, practices, efforts and ethics,” Gonsalves said. “The use and the unfairness of the use poses a real risk of eroding CBC’s trustworthiness and reputation in the eyes of the public.” At issue are a Conservative ad and tweets from the 2019 election that used clips from CBC news programming and other outlets and from the leadership debates. The ad, for example, showed a short clip of Prime Minister Justin Trudeau asking the viewer to “look …