I hate Constitutional law. Always have. I was the only one at the University of Pennsylvania law school that did not want to talk about the "big social issues" that are involved in Constitutional law scholarship. And yet, here I am.
There was a piece in the Illinois Construction Law blog entitled "Can Specific Government Implementation of Green Building Laws Violate Due Process?" The example provided was that the Illinois Capital Development Board has implemented guidelines Green Building Guidelines for State Construction
which do not offer the same “out” language of “or equivalent certification” as the Act and instead mandate LEED NC, with no exception for another standard.
The best Constitutional argument here is not actually one of "due process", but of impeding interstate commerce by favoring one private actor over another through regulation, a violation of the Commerce Clause.
However, where, as here, the state acts as a market participant, it is not subject to the same Constitutional restrictions as where the state is governing private entities. For example, where a state sources exclusively in-state materials for its own construction projects, the regulation is not restricted by the Commerce Clause. See, e.g. SOUTH-CENTRAL TIMBER V. WUNNICKE, 467 U. S. 82, 93 (1984) (“Our cases make clear that, if a State is acting as a market participant, rather than as a market regulator, the dormant Commerce Clause places no limitation on its activities.”) The state or federal government is free to make its own requirements for its purchases and projects, which may include setting a standard for its practices, like selecting the LEED standard.