How active should a pension fund be in the independent business decisions of the companies it invests in? In the case of a recent lawsuit filed against Sirius XM Radio by a Florida police pension fund, the answer seems to be "as much as they want to be," though it still may not help matters.

Reuters reports that the City of Miami Police Relief and Pension Fund has launched a suit against the satellite broadcasting company's board of directors for not taking a more defensive stance during the company's recent takeover by Liberty Media Corp.

The suit alleges that Sirius' actions breached the board's fiduciary duties and that the broadcaster failed to put up much of a fight or ask for a premium during negotiations to be taken over by Liberty.