In the WSJ, whose opinion pages are no longer behind a subscription wall:
Critically, however, "union pension funds" do not belong to unions. The funds are managed by trustees -- half appointed by the union and half by the companies that contribute to the fund pursuant to their collective-bargaining agreements. Under the federal employee benefits law (ERISA), which is administered by the Department of Labor, these trustees are to act "solely in the interest of the plan's participants and beneficiaries, and for the exclusive purpose of paying benefits and defraying reasonable administrative expenses," as the Department reiterated in an advisory opinion last month.
The Labor Department letter addressed a reported AFL-CIO plan to promote shareholder proposals that press companies to offer more generous employee health-care benefits, and that would require companies to disclose political contributions so shareholders could see if support was being given to candidates who don't share labor's views on health care.
Before undertaking "to monitor or influence the management of corporations," the department said, fiduciaries "must first take into account the cost of such action and the role of the investment in the plan's portfolio, and cannot act unless they conclude that the action is reasonably likely to enhance the value of the plan's investments." ...
In a word, unions are not entitled to use retirement funds to raise costs at the companies where the funds are invested. And unionized corporations are not required to permit this. Rather, management trustees and the Labor Department are obligated to prevent it.