Final answer:
Morgan and his partners were subject to congressional investigation for various issues, including Klan-related violence and corporate legal matters. Investigations often had major political implications, such as the impeachment proceedings against President Clinton and scrutiny of IRS actions.
Step-by-step explanation:
Morgan and his partners became the subject of a congressional investigation led by personalities such as President Grant and various members of Congress over different periods. The investigations ranged from looking into the violence perpetrated by the Klan in the 1870s to J.P. Morgan's U.S. Steel Corporation's legal challenges under President Taft's administration. Additionally, congressional investigations have also dived into various scandals including the Whitewater Development Corporation with linkages to the Clintons, and the surveillance of interest groups by the IRS.
Investigations like the impeachment of President Clinton, which started with accusations related to Whitewater and evolved to include the Monica Lewinsky scandal, demonstrated the political nature and high stakes of some of these inquiries. The role of congressional hearings and committees is often significant in addressing or bringing to light issues of national importance, as evidenced by the Joint Select Committee and the several notable investigations throughout the history of the United States.