In a copy of the lawsuit [PDF] posted online by Politico, the Kochs say they believe the widow of former chairman William Niskanen, who died in October, is barred from hanging onto his shares based on an agreement Niskanen signed when he joined the think tank in 1985.
The suit provides a look behind the scenes of the influential organization as well as the lives of its wealthy leaders.
Attached to the lawsuit was a copy of Niskanen's will, showing he left a third of his estate to his widow, Kathryn Washburn, a third to the Cato Institute and a third to the Institute For Justice, a law firm that fights for libertarian causes.
Originally founded in 1974 as the Charles Koch Foundation, the Cato Institute settled on its current name two years later.
Niskanen was chairman from 1985 until 2008, when he became its chairman emeritus and senior economist. Charles Koch was one of the original founders. David Koch became a shareholder in 1991, according to the suit.
In recent years, the only four people to own shares of the organization were the Koch brothers, Niskanen and co-founder Edward Crane III. Each had 25 percent voting interest, according to the suit.
The lawsuit said all the shareholders signed agreements pledging not to give or sell their shares to anyone else before first offering them to the Cato Institute. The brothers want the Kansas judge to force Washburn, who is the representative of her late husband's will, to offer his shares to the Institute so they can purchase them back from her.
The brothers are being represented by attorneys Daniel Crabtree and Heather Woodson of the high-powered law firm Stinson Morrison Hecker.