In this short paper, we show how hard evidence can be incorporated into the mechanism-design framework. We model the parties' inalienable decisions (evidence production) as distinct from an arbitrarily-designed message form. A mechanism specifies the message form and how the public decision is a function of messages and evidence. Our work is thus along the lines of Myerson (1982, 1991), whose mechanism-design analysis nicely distinguishes between inalienable private and public decisions.