Federal appellate judges weighed Monday whether state attorneys general waited too long to bring an antitrust lawsuit against Meta, the parent company of Facebook, over its past acquisitions of other social media platforms.

The central question to the proceedings is whether the states brought their claims as sovereign entities enforcing federal law or as nonsovereign entities that are essentially the same as private plaintiffs. The latter would mean the states had a four-year window to file the complaint over the social media giant’s purchase of Instagram in 2012 and WhatsApp in 2014.