While the judiciary often butted heads with the Mubarak regime, its contrarian decisions were often ignored.

WSJ: Panel Upends Egypt Election

Klein says the tension that existed when he and Gates butted heads from opposites sides of a federal courtroom has since dissipated.

FORBES: Legal Adversary Turned Ally

Ms Park lost the nomination to Mr Lee in 2007 and since then she and her loyalists have butted heads with the government.

ECONOMIST: The race to succeed the president gets under way

The announcement comes a little over a month after the president and the generals butted heads over Morsy's attempt to recall the country's disbanded parliament.

CNN: SHARE THIS

David Moss of HBS argues that such complaints are nothing new: American politicians have been squabbling about the role of government ever since Thomas Jefferson butted heads with Alexander Hamilton.

ECONOMIST: America is becoming a less attractive place to do business

In the course of his cyber-sleuthing, Reynalds has butted heads not just with the creators of some of these Web sites, but also the Internet service providers (ISPs) that host them.

CNN: The Internet war

Since these lawsuits, a war of words have been volleyed between Activision and EA. The two giant game makers butted heads last fall with Call of Duty: Black Ops and Medal of Honor going head-to-head at retail.

FORBES: Connect

"Fables of Faubus" shows how Mingus occasionally butted heads with corporate supervisors: The composer wrote a libretto that further castigated Orville Faubus, the segregationist governor of Arkansas, but Columbia refused to let him record the text (the title itself was nervy enough in that buttoned-down era).

WSJ: Charles Mingus | The Bassist in a Box | By Will Friedwald