THE Justice Department is building its case against Megaupload, the hugely popular file-sharing site that was indicted earlier this year on multiple counts of copyright infringement and related crimes. The company’s servers have been shut down, its assets seized and top employees arrested. And, as is usual in such cases, prosecutors and their allies in the music and movie industries have sought to invoke the language of “theft” and “stealing” to frame the prosecutions and, presumably, obtain the moral high ground.

Whatever wrongs Megaupload has committed, though, it’s doubtful that theft is among them.

From its earliest days, the crime of theft has been understood to involve the misappropriation of things real and tangible. For Caveman Bob to “steal” from Caveman Joe meant that Bob had taken something of value from Joe — say, his favorite club — and that Joe, crucially, no longer had it. Everyone recognized, at least intuitively, that theft constituted what can loosely be defined as a zero-sum game: what Bob gained, Joe lost.

When Industrial Age Bob and Joe started inventing less tangible things, like electricity, stocks, bonds and licenses, however, things got more complicated. What Bob took, Joe, in some sense, still had. So the law adjusted in ad hoc and at times inconsistent ways. Specialized doctrines were developed to cover the misappropriation of services (like a ride on a train), semi-tangibles (like the gas for streetlights) and true intangibles (like business goodwill).

In the middle of the 20th century, criminal law reformers were sufficiently annoyed by all of this specialization and ad hoc-ness that they decided to do something about it.