The Index to the USPC: Don't be Afraid

I usually tense up at the reference desk at when someone wants to know how you perform a preliminary patent search. Telling someone about the Index to the U.S. Patent Classification kind of feels like giving someone bad news.

Those who have never performed a patent search in earnest and those who regularly do this kind of research might wonder why I get this feeling. Is it really that bad?

Of course not. In fact, the Index to the USPC is a wonderful tool: it's well created, operates fairly smoothly, and users who are accustomed to indexes (like librarians and anyone who went to school in the pre-Google era) will probably find it to be very intuitive.

The problem is that keyword searching technology in other fields is so good that it makes people wary of indexes and what we librarians call controlled vocabulary. Often, librarians may scoff at keyword searching because of its obvious (to us, at least) shortcomings -- results are limited to the input of the user, relevancy may take a back seat to quick retrieval, searchers may forget synonyms; in general, we're worried that people are sacrificing accuracy for speed and convenience, perhaps without knowing it. Because index terms are assigned by a human being, not a computer, they are often going to be more comprehensive, more relevant, and more accurate. But they may be a pain to get to.

From the perspective of a non-librarian, however, I can understand that trading a little accuracy for the convenience and relatively flat learning curve of keyword searching might be just fine. I don't always go straight to subject headings when I search the library's catalog; though I greatly appreciate the work my colleagues have done creating a taxonomy for the mountains of information out there, sometimes I don't need to perform a comprehensive search. I just need something, and maybe something quick.

To get back to my point about the Index to the USPC and my unease when getting people started with it, it's that flat versus steep learning curve that tends to bum people out. Google, and, more specifically Google Patent Search, appear to work so well (and as a result create such confidence in users) because they get results. They get results for almost any search, even if you spell your terms wrong. If there isn't an exact match, Google will bring you a bunch of "close enough" matches. This type of research has virtually no learning curve.

Let me get off my soapbox and get back to patent searching. To properly do any kind of patent search beyond retrieving a known patent by number or an inventor's name, you have to rely on classes and subclasses, which you find through the Index. The Index, then, is scary because, unlike other research methods, there's a bit a slope to its learning curve. It's not much, mind you, but this type of searching is different than keyword searching.

There are a couple of reasons why this technique is necessary. Accuracy and comprehensiveness are crucial in patents: mistakes could mean that two people are granted the same patent for something. For the inventor, an incomplete search could mean missing a previous invention that disqualifies their invention from being granted a patent and wasting lots of money and time applying.

The reason keyword searching won't work is because a computer can only look for the words entered by its user. Since there's usually more than one way to describe any one thing, there has to be a way to link words and concepts that mean the same thing to the same patents. The Index is the way.

So don't be scared. It's just different, not much harder. Here's a quick rundown of the process:

1. Jot down some keywords that describe your invention or the invention you're looking for. Think of nouns and verbs, single words or phrases. Any of these can be included.
   
2. Words are listed alphabetically in the Index to the USPC. Click on a letter at the top, then either scroll down or use the "Find" function in your browser to seek out your word.
3. If you find your word, there will be two numbers next to it. The one on the left is the class, which is a broader category of technology. The one on the right is the subclass, which is a more narrow area. Click those numbers, and it will bring you to a listing of subclasses within a given class.
4. Click the "P" icon to the left of the subclasses, and you will find a list of patents that fall into that category.

As I mentioned before, the Index is actually quite an accomplishment. The creators knew that there are several different words for any given word or concept, and that they needed an accurate way to link these words to the appropriate group of patents.

For more information about patent searching using the Index, check out this tutorial from the University of Texas. And be free from fear!