The Patent Office and the courts have had a difficult time with computer software. The Patent Office refused until recently to hire Computer Science graduates as examiners, and in any case does not offer competitive salaries for the field. Patent examiners are often ill-prepared to evaluate software patent applications to determine if they represent techniques that are widely known or obvious--both of which are grounds for rejection.
Their task is made more difficult because many commonly-used software techniques do not appear in the scientific literature of computer science. Some seemed too obvious to publish while others seemed insufficiently general; some were open secrets.
Computer scientists know many techniques that can be generalized to widely varying circumstances. But the Patent Office seems to believe that each separate use of a technique is a candidate for a new patent. For example, Apple was sued because the Hypercard program allegedly violates patent number 4,736,308, a patent that covers displaying portions of two or more strings together on the screen--effectively, scrolling with multiple subwindows. Scrolling and subwindows are well-known techniques, but combining them is now apparently illegal.
The granting of a patent by the Patent Office carries a presumption in law that the patent is valid. Patents for well-known techniques that were in use many years before the patent application have been upheld by federal courts. It can be hard to prove a technique was well known at the time in question.
For example, the technique of using exclusive-or to write a cursor onto a screen is both well known and obvious. (Its advantage is that another identical exclusive-or operation can be used to erase the cursor without damaging the other data on the screen.) This technique can be implemented in a few lines of a program, and a clever high school student might well reinvent it. But it is covered by patent number 4,197,590, which has been upheld twice in court even though the technique was used at least five years before the patent application. Cadtrak, the company that owns this patent, collects millions of dollars from large computer manufacturers.
English patents covering customary graphics techniques, including airbrushing, stenciling, and combination of two images under control of a third one, were recently upheld in court, despite the testimony of the pioneers of the field that they had developed these techniques years before. (The corresponding United States patents, including 4,633,416 and 4,602,286, have not yet been tested in court, but they probably will be soon.)
All the major developers of spreadsheet programs have been threatened on the basis of patent 4,398,249, covering "natural order recalc"--the recalculation of all the spreadsheet entries that are affected by the changes the user makes, rather than recalculation in a fixed order. Currently Lotus alone is being sued, but a victory for the plaintiff in this case would leave the other developers little hope. The League has found prior art that may defeat this patent, but this is not assured.
Nothing protects programmers from accidentally using a technique that is patented, and then being sued for it. Taking an existing program and making it run faster may also make it violate half a dozen patents that have been granted, or are about to be granted.
Even if the Patent Office learns to understand software better, the mistakes it is making now will follow us into the next century, unless Congress or the Supreme Court intervenes to declare these patents void.
However, this is not the whole of the problem. Computer programming is fundamentally different from the other fields that the patent system previously covered. Even if the patent system were to operate "as intended" for software, it would still obstruct the industry it is supposed to promote.