Can sports teams keep rival fans away?

Williams filed suit this month against the Seattle Seahawks, the NFL, and Ticketmaster; he’s alleging the practice of restricting ticket sales to residents of certain states is a violation of federal law.

For January’s NFC Championship game in Seattle, the Seahawks limited online ticket sales to credit card holders who lived in Washington, Oregon, Montana, Idaho, Alaska, Hawaii, and some parts of Canada. Williams, a diehard 49ers fan and Las Vegas resident, couldn’t buy himself a ticket—exactly what the Seahawks intended.

Seattle isn’t the only team to try to protect its home-field advantage by limiting the number of tickets sold to outsiders. The Oklahoma City Thunder is currently keeping playoff tickets to a few neighboring states, leaving out the Memphis Grizzlies fans who might otherwise invade.