The politicization of state pension fund investments has once again come back to bite us — this time in coal stocks — harming taxpayers and government employees alike.

Under the Public Divestiture of Thermal Coal Companies Act of 2015, the California Public Employees’ Retirement System and California State Teachers’ Retirement System were required to divest their coal holdings by July 1, 2017. Unfortunately for taxpayers, this divestment coincided with a strong rebound in coal stocks. As the Sacramento Bee reported, “Stocks for 13 of the 14 companies are worth more than they were a year ago when the pension fund was divesting from the industry.”

This is just the latest example of politically motivated divestment policies, which have also targeted tobacco companies, firearms manufacturers, private prison operators, companies that might compete with state and local government workers for contracts, and companies that did business with apartheid South Africa. This has often had a significant negative impact on pension investment performance. CalPERS’ divestments cost it approximately $8 billion over a 15-year period, according to an October 2015 report from Wilshire Associates, CalPERS’ main investment consultant.

That has not stopped politicians from sacrificing the pension funds’ fiduciary duties for their own ideological crusades, however. During the current legislative session, lawmakers have put forward proposals to divest companies that build or finance the Dakota Access Pipeline, companies that work on President Donald Trump’s border wall, and Turkish bonds.

Not only do these measures hurt taxpayers, who must make up the difference whenever the pension systems’ investments underperform their assumed averages, they also harm many existing government workers, particularly at the local level, as the resulting higher government pension contribution rates mean that pension costs are taking up more of the budget and squeezing out government services — and government jobs.

It has gotten to the point that a number of unions, who typically support the Democratic lawmakers that push for such divestment policies, have begun to speak up about the perils of ideological investing.

“It’s time for CalPERS to re-evaluate their investment strategies and focus more on improving their investment returns and less on ‘socially responsible’ investments,” Steve Crouch, director of public employees for the International Union of Operating Engineers, which represents roughly 12,000 state maintenance workers, told the Bee.

“We cannot afford to lose funding for law enforcement officers in exchange for a socially responsible investment strategy,” Police Lt. Jim Auck, treasurer of the Corona Police Officers Association, told CalPERS board members at a meeting in May. “Your fiduciary responsibility is to the employees, the employers and the taxpayers of this state, not to the many agendas of the many special interests that dominate Sacramento politics.”

Playing politics with government workers’ and retirees’ pension funds does not serve them or the rest of the taxpayers in the state. This is all the more reason to remove politics from the equation altogether and switch to a 401(k)-style defined-contribution system that lets workers invest their retirement funds as they please.