The Ho-Chunk Nation is reworking its federal lawsuit against prediction market company Kalshi , shifting the case away from a general attack on sports wagering and toward a more focused dispute over tribal gaming law and advertising claims.

In a filing submitted May 22 in the U.S. District Court for the Western District of Wisconsin and seen by ReadWrite, the tribe asked a judge for permission to amend its complaint after part of the original case was dismissed earlier this month. The revised complaint centers on the Indian Gaming Regulatory Act, or IGRA, which the tribe says provides clear legal authority showing Kalshi falsely promotes nationwide legal sports betting.

The case has become one of several major legal fights surrounding prediction markets and sports-related event contracts.…