A Wall Street Journal op-ed has a brief history of political targeting by the IRS. The prime offenders were Franklin Roosevelt, Kennedy, Nixon, and Clinton. (I suppose Woodrow Wilson didn’t bother with the IRS; he just locked up his opponents for sedition.) It’s interesting that in that group, Nixon is the only one most journalists are able to remember.
There’s also this appalling statistic:
The IRS has usually done an excellent job of stifling investigations of its practices. A 1991 survey of 800 IRS executives and managers by the nonprofit Josephson Institute of Ethics revealed that three out of four respondents felt entitled to deceive or lie when testifying before a congressional committee.