US History Trivia: What Constitutional amendment is the least litigated?

The US Constitution is obviously the ultimate legal principle to which laws in this country must be held.  As a result of its exalted legal status, the Constitution and its various amendments have been litigated numerous times - but some of its 27 amendments have been litigated more times than others.  Off of Pocket Trivia: US History - Which of these Constitutional amendments is the least litigated?  Is it:

• The 7th Amendment
• The 19th Amendment
• The 3rd Amendment
• The 18th Amendment

The answer to this one is the 3rd amendment.  This amendment reads as follows:

"No soldier shall, in time of peace be quartered in any house, without the consent of the owner, nor in time of war, but in a manner to be prescribed by law."

The amendment itself was a reaction to the frequent practice of British soldiers essentially taking over an owner's home or land during periods of war, with or without the owners consent.  This being said, this is a practice that essentially stopped occurring in the United States, largely since there were so rarely wars actually fought on U.S. soil since the American Revolution.

There have been virtually no cases directly invoking the third amendment, though it was referred to in other cases discussing the right to privacy and limits on the power of the President.