Valley Forge, Pa.

SHOULD Home Depot’s board report each year on the company’s political policies and spending? In a groundbreaking vote at the company’s June 2 annual meeting, Home Depot’s shareholders will have the chance to vote on a nonbinding resolution of support for the company’s policies on, and future plans for, political contributions.

The vote was made possible because the Securities and Exchange Commission rightly decided in March to allow proxy proposals that require public companies to permit their shareholders to weigh in on their political spending.

This means that, notwithstanding the Supreme Court’s decision last year that laws limiting corporate political contributions violate constitutional free speech principles, the game is far from over. Shareholders — not self-interested corporate managers — should, and can, decide policies on corporate political contributions.

What makes this strengthening of shareholder rights particularly important is that over the past 50 years control of corporate America has shifted from individual stockholders to institutional stockholders. But these institutional investors have been unwilling to challenge political activities by corporate boards, even when those activities are not in their shareholders’ interests.

Our nation’s money managers now hold 70 percent of all shares of American corporations, compared to a mere 8 percent in the 1950s, giving them absolute voting control. To be sure, these money-management agents are duty-bound to represent their principals — mutual-fund shareholders, for instance — but have not always honored this responsibility.

In fact, for decades, with a handful of exceptions, the participation of our institutional money managers in corporate governance has been limited, reluctant and unenthusiastic. Perhaps they feared angering clients whose pension and thrift funds they manage — that is, the very corporations whose shares fill their investment portfolios. It is an obvious conflict of interest, however often denied.

To make matters worse, most of our large institutional money managers are themselves owned by giant United States and global financial conglomerates. The shares of those conglomerates, in turn, are held in their own portfolios. I don’t expect this web to be easily untangled.

And yet I believe that, in the wake of the Supreme Court case, known as Citizens United, the institutional investor community has an obligation to act. Institutional investors should insist that the proxy statement of each company in which they invest contain the following: “Resolved: That the corporation shall make no political contributions without the approval of the holders of at least 75 percent of its shares outstanding.”

Such a “supermajority” requirement is necessary because of the inevitably wide range of views that characterize any shareholder base. As it happens, 75 percent is halfway between a simple majority and the standard (under Delaware corporate law) that requires a unanimous shareholder vote to ratify a gift of corporate assets other than for charitable purposes.

For all its faults, the Citizens United ruling upheld the disclosure requirements of the campaign financing law, and I had hoped full disclosure might limit corporate contributions. But in fact, corporations are able to exploit provisions in the law governing nonprofit groups to make lavish political contributions without disclosure, making it easier than ever for cash to subvert our political system. Action to limit contributions at the corporate level is therefore urgent.

Indeed, the Supreme Court itself put the onus on shareholders to control corporate political giving. In his opinion for the majority in Citizens United, Justice Anthony M. Kennedy predicated the First Amendment right of free speech on the ability of shareholders to ensure that the speech reflects their views rather than diverting corporate assets for the benefit of executives. He suggested that any abuse could be corrected by shareholders “through the procedures of corporate democracy.”

In the Home Depot case, which was brought by NorthStar Asset Management, a Boston money manager, a vigilant S.E.C. has allowed our shareholders to take that first step toward democracy. The critical battle over political spending by corporations has now been joined. For the first time, the financial institutions that now control corporate America will have to stand up and be counted: the ballots are before them, and they will have to vote yes or no, or abstain. While mutual funds, our largest holders of stocks, are now required to publicly report how they voted during the year, pension funds are not; they should be.

Fortunately, the Home Depot shareholders aren’t alone: similar proposals are also included in the proxy votes now being solicited by Citigroup, I.B.M. Charles Schwab, Prudential, JPMorgan Chase and others. From this modest beginning, I hope a groundswell will develop that will give corporate owners a say not only over political contributions, but many other policies — executive compensation being the most obvious example.

The outcome of these votes this proxy season will be a powerful indication of whether our money managers are observing their fiduciary duty and putting the interest of the small investors and pension funds that are their clients before their own. America’s institutional investors must stand up to the Supreme Court’s misguided decision and bring democracy to corporate governance, recognize conflicts that arise from the interlocking interests of our corporate and financial systems, and take that first step along the road to reducing the dominant role that big money plays in our political system.

John C. Bogle is the founder and former chairman and chief executive of the Vanguard Group.

A version of this op-ed appears in print on May 15, 2011, on page WK9 of the New York edition with the headline: The Supreme Court Had Its Say. Now Let Shareholders Decide. Order Reprints | Today’s Paper | Subscribe