Q: If there was a patent on an already patented product, what would I need to change about that product?

A: Be careful. Consult with an attorney.

The patent allows you to practice your improvement, but you are still bound by the active patents covering elements that are part of your invention.

The change needs to be novel and non obvious.

A: If you know that there is a patent on a certain type of spray bottle that you want to sell, then you need to contact a patent attorney about it. Here is what the attorney will be able to do for you:

Firstly, the attorney will check if there really is a patent. The patent may have already expired (it is very costly to redesign a injection mold which may list the patent, so under the new law, it is OK to list old patents). The patent may have been abandoned due to non-payment of fees. Or the patent has been litigated, and has been found to be invalid. This may cost you a few hundred or over a thousand dollars, if you just want the attorney to tell you orally, or a few thousand if you want it in writing that you can use if you are ever sued by the patent owner. This would be the best scenario.

Secondly, the attorney will check if it looks like that a court could find you that you are indeed infringing. You would ask for a Non-Infringement Opinion, which would say that you are not infringing. Hopefully, it is going to be very clear that you are not infringing.

Thirdly, if the attorney thinks that you are not infringing, but it is not very clear that you are not infringing, then the patent attorney will give you a detailed analysis why you are not infringing. This is not a good position to be in, because even if you are not infringing, you may still get sued -- if your attorney is right, you may win, but it is still going to be expensive for you business.

Fourthly, if your attorney cannot provide you with a Non-Infringement Opinion (of course, your attorney won't put down in writing that you are infringing), or if it is not very clear that you are not infringing, then you should consider doing a redesign. The design should be different enough from the patent claims, that it would be clear that you are not infringing. An easy redesign is just to use any design that is at least 20 years old -- almost nothing that is 20 years old or older is under a patent.

Fifthly, if your attorney cannot provide you with a Non-Infringement Opinion or if it is not very clear that you are not infringing, and you cannot do a redesign, then you may consider getting a Patent Invalidity Opinion done. This opinion essentially says that the patent is for some reason invalid.

Sixthly, if your attorney cannot give you a Non-Infringement Opinion and Patent Invalidity Opinion, and you cannot redesign, then it becomes a business decision of what you want to do. People in such a situation license the patent, or just carry on selling the product despite the attorney telling them that they can't, or just stop selling the product.

Good luck, and if you need help, I've addressed plenty of these situations.