Laws of general applicability that require persons to meet certain general requirements of citizenship, such as paying taxes, cannot be avoided by the fact that they indirectly make it more difficult to fulfill a purely religious duty, such as a member tithing a certain amount to his church or making a pilgrimage to a shrine in a foreign country.

FORBES: Render Unto Caesar - Mormon Tithe Not A Necessary Expense In IRS Collection Case

The Cohan Rule is most classically applied to travel and entertainment, but can apply to virtually any item not specifically subject to heightened substantiation requirements (such as certain travel and meal expenses, passenger automobiles, computers and cell phones).

FORBES: Tax Return Filed? Now Consider Your Records

U.S. Secretary of Education Arne Duncan said last month that if Congress didn't overhaul No Child Left Behind soon he would waive certain requirements in exchange for states adopting changes he supports, such as linking teacher evaluations to student achievement and expanding charter schools.

WSJ: States Test No Child Left Behind

Capital expenditure would rise if the airstrip had to meet certain standards on runways, such as length, width and requirements on runway end safety areas.

BBC: Old Man of Storr, Skye

The Amazon offers don't carry minimum point requirements, but consumers can't use their rewards for certain items, such as Kindle downloads.

WSJ: The New Credit-Card Rewards Programs