There is no specific percentage difference. It is very much a factual, case-by-case evaluation. The test is whether an ordinary observer would think the patented design and yours are substantially the same. What exactly constitutes "substantially the same" is any body's guess.
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There's no objective test for how different (or similar) designs must be to not infringe (or infringe). The subjective test is whether an ordinary observer, who knows what else exists, would think there is a substantial similarity between the designs. It's a very fact-specific analysis, in every case.
I think you'd need to hire an attorney and get an opinion, if you're planning on making sunglasses to design around someone's design patent...
Anything I post on Avvo, a public forum, is intended as general information based on the facts provided, and is not legal advice or a legal opinion. My posts do not create any attorney-client relationship, and any contact with you beyond these posts will start with disclosure of opposing parties to allow me to check for conflicts. You should not rely solely on these posts to take or not take any particular action. You should speak with a competent attorney before taking further action.
You should read a few court decisions that apply the design patent infringement analysis to get a feel for how it's done [visit the link below]. Then you and your own patent attorney need to apply that analysis to the facts of your case. Good luck.
The above response is general information ONLY and is not legal advice, does not form an attorney-client relationship, and should NOT be relied upon to take or refrain from taking any action. I am not your attorney. You should seek the advice of competent counsel before taking any action related to your inquiry.
The standard that is still valid is from a 2008 Federal Circuit opinion from Egyptian Goddess v. Swisa, Inc where the court held that a design patent is infringed "if an ordinary observer would think that the accused design is substantially the same as the patented design..." All of this is in the context and consideration of all prior art.
Thanks for reading! Note, this is not legal advice, it is simply some of my thoughts regarding the question posed. There is no attorney-client relationship. I am not your attorney and you are not my client.
This is the kind of question that is so fact-intensive it requires an IP lawyer to actually look at the material (and I try hard to avoid saying that in ip questions on here).
I have litigated quite a few design patent cases for sunglasses. It really is a very fact intensive analysis that involves looking at the various areas. You should consult an attorney that does design patent cases and he/she can go over some of the issues in more detail.
Disclaimer -- The information provided in this response is for informational purposes only and should not be construed as legal advice. This information is not intended to create an attorney-client relationship. Attorney Ishimoto is licensed only in California.
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