The Constitution guarantees due process and equal protection under the laws. Democrats in California are pushing legislation that would eviscerate both and set a terrifying precedent that threatens to send any project opposed by liberals—toll roads, housing developments, even private schools—into a purgatory of regulation.

For nearly two decades, Sen. Dianne Feinstein and a rear guard of environmentalists have been trying to block the Los Angeles-based company Cadiz from developing a groundwater basin in the Mojave Desert. In 1998 Cadiz began plans for a groundwater bank on 50 square miles of private land in the Mojave overlying two huge watersheds that have accumulated tens of millions of acre-feet of water over the centuries and could sustain the state’s 39 million residents for years.

Cadiz wants to store runoff from the Colorado River and mountain streams during wet years like the last one and transport some of the groundwater each year—about 50,000 acre-feet—to urban areas. A groundwater bank is akin to a savings account in which owners save earnings in times of plenty to draw down in lean years. Storing water underground reduces evaporation and environmental impacts, which is why green groups like the Natural Resources Defense Council have long preferred groundwater banks to reservoirs.

The U.S. Interior Department approved Cadiz’s plan in 2002, but this was only the start of a tortuous regulatory review that seems to have no end. Mrs. Feinstein has lobbied regulators at all levels to intervene, claiming the Cadiz project would harm the Mojave’s rich wildlife, including the bighorn sheep and desert tortoise.

To assuage environmental objections, Cadiz scaled back its proposed water exports by two thirds and negotiated to use Arizona & California Railroad’s right of way to build a 43-mile underground pipeline connecting to Southern California’s water supply. In 2012 the Santa Margarita Water District approved a final environmental impact report under the California Environmental Quality Act, concluding that the project’s only significant effects would be temporary dust from construction and population growth made possible by an expanded water supply. San Bernardino County also signed off on a plan to ensure Cadiz’s operations would not threaten the aquifer’s water quality or desert wildlife.