WASHINGTON — Supreme Court justices on Monday weighed copyright protections for publishers, creative artists, and manufacturers in a global marketplace in a case that has attracted the interest of Costco, eBay, and Google. The outcome has important implications for consumers and multibillion dollar annual sales online and in discount stores.

The court was about the only Washington institution open on Monday. The justices and spectators who braved the rain and wind saw a book publisher face off against a Thai graduate student in the United States who resold the publisher’s copyrighted books on eBay after relatives first bought nearly identical, cheaper versions abroad.