A Florida attorney who represents the billionaire Marshall family, which owns a 16% stake in Koch Industries, will have to face a lawsuit in Texas alleging his letters to the wealthy multinational corporation’s CEO were defamatory to one Marshall family member.

Lawyer Edwin Hunter argued that a probate court in Harris County, Texas, did not have jurisdiction over him since he lives in Florida. But Houston’s Fourteenth Court of Appeals rejected that argument, listing examples of Hunter advising Marshall family members about legal matters in Texas.