The briefs, filed a week before oral arguments, offered sharply differing accounts of China’s influence over the site and the role of the First Amendment.

© Haiyun Jiang for The New York Times

The briefs, filed a week before oral arguments, offered sharply differing accounts of China’s influence over the site and the role of the First Amendment.

The president-elect took no position on the app’s First Amendment challenge to the law, which sets a Jan. 19 deadline to sell or close the popular platform.

The company and its Chinese parent invoked the First Amendment in urging the justices to step in before a deadline to sell or be shut down.

The company and its Chinese parent invoked the First Amendment in urging the justices to step in before a Jan. 19 deadline to sell or be shut down.