When Justice Joseph Story said in 1841 that patent cases are closer than any other kind to “the metaphysics of law,” he could have been speaking for the frustrated jurist or patent clerk of any era. What happens when the differences in what two parties claim to have created are narrow or nuanced to the point of being indistinguishable?

The dilemma is especially sharp in the era of digital technology. After all, patents on physical things can be measured and felt. But what about the world of software, where much innovation is subtle and conceptual? What about Google and Oracle’s fight over Patent No. 7,426,720, “System and method for dynamic pre-loading of classes through memory space cloning of a master runtime system process”? In a field whose products are built in layers, with each successive innovation representing a small and sometimes imperceptible shift in code, drawing a line between the old and the new can look like an exercise in counting the number of angels that can dance on a microchip.

Yet Congress seems interested in trying. Patent reform is one of the few issues on which there is any bipartisan agreement left, and if Congress takes it up, it’s going to have to grapple with the ways in which the legal architecture of yesterday is unfit for the digital world of today.

If Congress listened to the people who write the code, it might abolish software patents altogether. The views of many engineers can be summed up by American programmer and id Software founder John Carmack: “The idea that I can be presented with a problem, set out to logically solve it with the tools at hand, and wind up with a program that could not be legally used because someone else followed the same logical steps some years ago and filed for a patent on it is horrifying.”

Writing on the forums of Y Combinator, another coder had this to say: “I can't stand the idea that I might be at my computer, working with code, and develop something independently which later causes me to get sued. Abolish all software patents.” A different coder put it this way: “Coding around patents is like walking blindfolded through a minefield.”

For the companies that employ such coders, the costs of patents are tremendous: In 2011, Apple and Google spent more on patent lawsuits and purchases than on R&D. So it’s no wonder that Apple CEO Tim Cook has described the patent landscape as “maddening” and “a time suck.” But at the same time, his company has amassed an arsenal of patents that allows it to sue its competitors into submission.

Cook would surely paint that arsenal as a defensive one — but every other tech CEO would say the same, and we all know that arms races can spark destructive wars, whatever the generals’ intentions. In fact, we can quantify the destruction: a Boston University study found that from 1984 to 2009, the costs of patent litigation outweighed economic benefits and added up to as much as $1.49 trillion.

Remember, our Constitution established a patent system to accomplish a specific goal: “to promote the Progress of Science and useful Arts.” That makes sense: Few people would put the time and money into innovating if they were certain to be ripped off by copycats. But when our patent system diverts a trillion dollars from the progress of science to the progress of law firms, it has arguably become self-defeating.

Of course, we can hardly expect Congress to do anything so utopian as abolishing software patents. But more limited action is likely. Look for legislation against “patent trolls,” firms that hoard patents and file dubious lawsuits in bulk, all without developing any new products themselves.

Taking on patent trolls makes political sense — and not just because they’re an easy scapegoat for the patent system’s broader troubles. More than that, patent reform is a reliable political trope. It’s useful as a line in a speech about innovation. It’s an answer to that perennial political question: “Well, what are you actually going to do about the economy?”

But just as we should be realistic about Congress’ aims, we should also be realistic about (limited) patent reform’s economic impact. Anyone expecting patent reform to unleash a suppressed torrent of innovation should look at history. The story of our most famous innovators is also the story of their lawsuits: Inventors from Eli Whitney to the Wright brothers to Samuel Morse have struggled with patent law, copyrights, and copycats.

What does that tell us? That the patent landscape has always been a maddening time suck. That innovation has happened anyway. And that we can expect reform to help on the margins — without imagining that a fifth-dimensional iPhone-Google Glass-Oculus Rift hybrid will snap into existence the moment the president signs the bill.