You find out that your competitor has a patent and might be threatening to sue you. What can you do?
The fact that a patent has been granted does not mean that it is valid. If the patent is an innovation patent, you need to find out whether it has been certified. If it hasn’t been certified, that means it hasn’t even been examined yet.
If the patent is a standard patent or a certified innovation patent, the most common way to question its validity is to try to find documents which show that the invention was not new when the patent application was first filed.
The invention has to be new when compared with any document published anywhere in the world. There is no way the patent office examiner can look at every possible relevant document, so you may be able to find documents that the examiner missed.
Another common way to contest the validity of a patent is to argue that the claimed invention does not have an inventive step. It is usually not hard to find university professors and other experts who are happy to argue in court that an invention is completely obvious.
There are several other grounds on which you can contest the validity of a patent. You can argue that the true inventor was someone different from the person claimed by the patent owner, or that the patent was obtained by fraud, or that the patent does not meet other technical requirements.
If someone claims you are infringing a patent, you can often find a range of ways to argue the case. However, it is expensive and time-consuming to fight a patent case in court, so you need to be aware of the strengths and weaknesses of your case before you start.