Sanchez was calling for the state to take over HISD schools when a man dumped water over his head and ran.
RELATED: Treasurer doused with water while talking about HISD's future
ABC13 Eyewitness News obtained the lawsuit Friday morning, and learned that Sanchez is suing the man for $1 million.
Sanchez was taking part in a press conference at Northwest Mall, across the street from HISD's Hattie May Administration Building, when things got pretty heated.
The lawsuit claims Sanchez suffered mental anguish.