A public battle involving financial misconduct allegations at the Ma Ying-jeou Foundation is causing political turmoil and raising concerns about the former leader's legacy.

What began as an internal personnel dispute at the Ma Ying-jeou Foundation has evolved into an increasingly bitter and publicly fought battle that is engulfing the former Taiwanese leader whose political legacy it is meant to preserve. Allegations of financial misconduct at Ma’s foundation have spiralled into criminal complaints, publicly traded accusations among long-time allies and an unprecedented intervention by his family. The dispute has also raised broader questions about Ma’s health,...