From "Wealth of Ideas" e-newsletter, April 2005

Prospective inventors often have ideas about patents that aren't quite true – such as the belief that a patent, once obtained, will be easy to license to a large company, thereby making the inventor fabulously rich. Unfortunately, it isn't necessarily so. It is difficult for an individual inventor to license his patent, and few inventors succeed.

Read on for a few of the other major misconceptions concerning patents.

Misconception #1: A patent gives you the right to practice your invention. First, a patent does not provide positive or affirmative rights at all. A patent is strictly a negative or exclusionary right – the right to exclude others from using, making, selling or offering for sale the patented invention.

Furthermore, no patent is an island. That's because all patents have prior art, meaning patents, publications or products that precede the patent in question. So just because you have a patent doesn't mean that you have the right to practice the patented invention without having to license someone else's patent. What a patent does give you the right to do is to sue someone who is practicing your patented invention without your permission.

Which brings us to the next misconception:

Misconception #2: If an alleged infringer is doing something similar enough to your patented invention, it must be infringement. This is the misconception of those that think that a patent tangentially related to computer software simply must be infringed by Microsoft, and infringement can be found if you just look hard enough and squint your eyes in a certain way as you read the patent claims. But the fact is that the scope of a patent is limited to its claims, and each limitation of the claim must be met by the allegedly-infringing product or process in order for infringement to exist (this is known as the "all elements" rule of patent infringement).

For more on what constitutes patent infringement, see our September 2004 feature article, "Is My Patent Infringed?"

Misconception #3: Rights accrue from the patent's filing date. The right to collect damages for patent infringement really only begins when the patent actually issues – not when you file the application. (After the patent issues, certain limited rights commencing on the date of publication of the patent application may retroactively accrue.) The filing date is important in other ways – for instance, if you have publicized your invention and need to file within the one-year "grace period" (see "Patent Basics: Statutory Bars", December 2004).

There are many more patent misconceptions besides these, and even if you are a patent-holder, you may not understand patent law as well as you think you do. That's why we always recommend that you consult a patent attorney if you believe that your patent is infringed (or if someone accuses you of infringement).