Scott Pruitt has done good work reining in his predecessor’s regulatory overreach. But that only makes the EPA Administrator’s decision late last week to rubber stamp a violation of due process toward a mine proposal in Alaska all the more disappointing.

The Environmental Protection Agency said it will no longer seek to withdraw the Obama Administration’s pre-emptive veto of the proposed Pebble copper and gold mine in southwest Alaska. The Obama EPA issued that unprecedented veto in February 2014, blocking Pebble’s progress...