The spirit of the law as passed was to stop cable companies capturing and rebroadcasting over-the-air TV signals without compensation. So it shouldn't be too surprising that the Supreme Court made the judgement they did.
It's quite simple: when this law was created, was Aereo's use case considered? If the answer is 'no', then you can expect the law to be refined to cover it at a later date. Odd legal loopholes don't get to stand just because they've been around for a while.
On if such a performance was private or public: the decision said that it was a moot point as the "commercial objective" of Aereo was the same as if it were public. The law as it stands did not intend to separate private and public performances.
Also, how about applying the spirit of the Statute of Queen Anne. Wouldn't like that one, I'm thinking.
"Spirit of the Law" - humbug.
We don't, no. The Supreme Court does, however.
The intention of the changes to the Copyright Act (which Shivetya has detailed better than I can[1]) was to stop basically what Aereo is doing, albeit back in the 1970s with cable companies. The legalese reflected the technology of the time. Aereo found a technical loophole that allowed them to continue to do it, but all the while they were violating the spirit of the law.
Which is, of course, legal. Until it isn't.
Antennas are legal. Manipulating airwaves to be played on a TV is legal. Long antenna cables are legal. Putting an antenna on my neighbor's roof is legal. Paying my neighbor rent for such a thing is legal. Storing broadcast content is legal. Paying for devices to do such a thing is legal.
Aero by many is seen as a tool to make use of those transmission on public air waves therefore in the sprit of the law.
But yes, horizontally scaling systems comes at a cost, sometimes they are more inefficient, sometimes they cost more, but in the long run if it helps you meet the goals of the business it shouldn't be illegal.
They said themselves that the reason each user has an antenna is because it was what allowed them to legally operate. Their hardware setup was entirely based around a loophole in existing law. Ironically, it's awful horizontal scaling, too - if a single antenna breaks there is no backup, the user assigned to it loses their TV signal.
It's not the array of antennas that boggled me the most, it was the racks and racks of servers encoding the exact same show hundreds or thousands of times in parallel.
That's expensive and inefficient. The only reason they did it was to exploit a potential loophole in the current law - and now the Supreme Court has effectively closed that loophole.