Following government rules is often a tough enough task. But when federal agencies secretly move their own rules' goalposts and then threaten millions of dollars in fines for noncompliance, it can be devastating.

Ask Jack LaPant. In 2011, the rural farmer in Tehama County, Calif., planted 900 acres of winter wheat on his property. Before he ever put a plow to the soil in his field, he sought the official views of both the U.S. Department of Agriculture Farm Services Agency and the Natural Resources Conservation Service. Both agencies assured him that since growing wheat would be consistent with past use of the land, he could legally proceed as planned.