In 1913, Henry Ford of the Ford Motor Company started up the first-ever production line for motor vehicles. The Model T, which had previously taken 12 hours to assemble, could no be built in a fraction of that time -- about an hour and a half -- and therefore also done so at a much lower cost than previously. Car ownership in America quickly rose.

And with that came a problem: with more cars on the road, there were now more cars for ne'er-do-wells to steal, and the law hadn't quite caught up to the changes in technology.  As the FBI's website explains, "in these early days, cars were easy to steal, [and] as car sales exploded, so did automobile thefts. Professional gangsters, insurance scammers, petty thieves, and even kids looking for a joy ride all got in on the action. By 1918, more than 27,000 motor vehicles were being stolen each year in 28 of the nation’s largest cities. Cars quickly became enablers of crime, too. They made it much easier for crooks to rob banks, transport stolen goods, kidnap women and children, and evade police simply by crossing jurisdictions or state lines." 

That changed in October of 1919 when Congress passed the Dyer Act. At the time, the law stated, in pertinent part, that "whoever shall transport or cause to be transported in interstate or foreign commerce a motor vehicle, knowing the same to have been stolen, shall be punished by a fine of not more than $5,000, or by imprisonment of not more than five years, or both." Per the FBI's website, "the law was a game changer," allowing the federal government to help local authorities investigate and ultimately prosecute car thefts.

But in 1931, a man named William McBoyle beat the law. At some point either that year or the year before, McBoyle transported a stolen airplane from Ottawa, Illinois, to Guymon, Oklahoma, a distance of about 900 miles. For some reason, the authorities in Oklahoma decided they couldn't prosecute McBoyle for the crime -- landing a stolen plane in Oklahoma wasn't a crime, perhaps? -- and the police in Illinois were powerless to enforce their laws in Oklahoma. The federal government stepped in, arresting McBoyle and charging him with violating the Dyer Act. McBoyle was convicted, fined $2,000 (about $35,000 today), and sentenced to three years in prison. Not wanting to pay that money or serve that time, McBoyle appealed, and ultimately, his case ended up before the Supreme Court. He didn't argue that the plane wasn't stolen nor that he didn't transport it to another state -- those facts were as clear as the skies he flew through. Rather, he argued that the Dyer Act only applied to "motor vehicles" and an airplane wasn't one. Congress, when writing the law, defined "motor vehicles" as "an automobile, automobile truck, automobile wagon, motor cycle, or any other self-propelled vehicle not designed for running on rails," not something that takes to the sky.

By today's standards, that may seem laughable; an airplane is a "self-propelled vehicle not designed for running on rails," after all. But the Supreme Court sided with McBoyle. The Court noted that "in everyday speech 'vehicle' calls up the picture of a thing moving on land." Further, in drafting the law, Congress wasn't thinking about airplanes; the Court opined that "airplanes were well known in 1919 when this statute was passed, but it is admitted that they were not mentioned in the reports or in the debates in Congress." Congress, the Court found, didn't make it clear that the Dyer Act applied to stolen airplanes (and may not have even considered it at the time). As a result, despite the fact that McBoyle had taken a stolen airplane on a 900-mile quest, he hadn't actually violated the law. as written.

And that was enough for the Court to decide in McBoyle's favor. In a unanimous decision for the Court, Justice Oliver Wendell Holmes wrote that "although it is not likely that a criminal will carefully consider the text of the law before he murders or steals, it is reasonable that a fair warning should be given to the world in language that the common world will understand, of what the law intends to do if a certain line is passed." The Dyer Act, as applied to planes, did not do that, and McBoyle was set free. He had successfully taken a stolen plane to Oklahoma.

Congress ultimately got around to fixing this plane-sized loophole in the Dyer Act, but it took a while. In 1945, well after McBoyle had pulled off his Supreme Court-sanctioned heist, Congress revised the Dyer Act to include airplanes. Today, the law states that "whoever transports in interstate or foreign commerce a motor vehicle, vessel, or aircraft, knowing the same to have been stolen, shall be fined under this title or imprisoned not more than 10 years, or both." So please, don't try to pull a McBoyle; it won't work.