You can learn a lot by searching patents, but what you learn can sometimes be dangerous. If a court should ever find that you infringed on a patent knowingly, you might have to pay triple the damages, together with attorney fees.
You can protect yourself by obtaining a lawyer’s written opinion stating either that there is no infringement or that the patent in question is invalid. However, such an opinion can cost tens of thousands of dollars. So if you search patents regularly, getting an opinion for each patent you know about is just not practical. And what does it really mean to know about a given patent?
At one extreme on the knowledge continuum is the large, evil corporation that has studied a smaller competitor’s patent and then ignored it, deciding, say, to outspend the competitor in court if sued for patent infringement. At the other extreme is the company accused of knowing about a patent simply because one of its engineers has stored a copy of it in his files, unbeknownst to bosses and colleagues. In between these two extremes lie the hard cases.
It’s perfectly legal to study existing patents in order to know how to design around one of them. But what if a jury decides that you haven’t really sidestepped a patent? You can use that design-around attempt as evidence that your infringement was not willful. Unfortunately, an unsuccessful design-around attempt does not automatically produce a finding of no willful intent.