Never one to shy away from controversy,
"Information or accusations relative to rule violations must be handled by institutions filing those concerns with the conference office through a formal process, and institutions must refrain from discussing those concerns publicly," Commissioner Larry Scott said in a statement.
Leach made his comments earlier in the week, echoing a similar complaint from last season.
"I think they still steal signs, and we'll have to keep an eye on that," he said of Arizona State on Monday. "That is a very unsavory practice they have, so we'll have to do what we can to defend against it."
No rules prohibit a team from "observing an opponent's offensive or defensive signals," the Pac-12 stated.
Washington State plays at Arizona State on Saturday in a crucial match-up of teams vying for the conference championship game.