Indiana Pi Bill
| Style over substance|
The Indiana Pi Bill was a proposed Indiana law which would by legal fiat "square the circle" and in the process, legally redefine pi to a nice, clean 3.2, from the unending 3.1415926535897… more generally believed. It was introduced to the state legislature at the behest of Edwin J. Goodwin, a physician and avid pseudomathematician, who by 1897 believed he had resolved all three of the ancient unsolved compass and straightedge construction problems: trisecting the angle, doubling the cube, and squaring the circle (never mind that these were already all known to be impossible).
A loyal Hoosier, he deigned to share his newfound knowledge with the state of Indiana (and only Indiana), and it was introduced to the Indiana House of Representatives as Bill for an act introducing a new mathematical truth and offered as a contribution to education to be used only by the State of Indiana free of cost by paying any royalties whatever on the same, provided it is accepted and adopted by the official action of the Legislature of 1897 as bill #246. The bill stated that previous values for pi had been found "wholly wanting and misleading". The full text really must be read to be believed.
The bill easily passed committee and was unanimously passed by the house. Representatives received it favorably, with one gushing that "The case is perfectly simple. If we pass this bill which establishes a new and correct value of pi, the author offers our state without cost the use of his discovery and its free publication in our school textbooks, while everyone else must pay him a royalty." 
Fortunately for generations of future Indianans, C.A. Waldo, a professor of mathematics from Purdue University, was in town in order to procure the annual state funding for his university. He read the bill and talked sense into enough members of the Senate that the bill was never passed.
There have been a lot of efforts to explain away the approximation to pi, and also some folklore about the attempts.
The most famous episode took place in the 19th century, when the legislature of Iowa supposedly considered a resolution to make pi legally equal to 3, based on the Biblical passage. Actually, the effort was the brainchild of a well-meaning but not overly mathematical legislator to make things easier for practical calculations by legislating a standard and simple value of pi. If we can define other weights and measures, why not pi? The proposal had very little to do with the Bible and died a quick death in committee.
A fake news story making the rounds in the early 2000s reported that Alabama had passed a bill setting the value of pi at 3. This usual controversy stems from the value of pi being 3 according to 1 Kings 7:23-26. It was originally posted to talk.origins as a parody of attempts to legislate creationism, but the fake tagline was lost somewhere along the way so it resembled a genuine news item.