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Is it possible to infringe a patent by infringing dependent claims and not independent claims? Does that mean I just need to check independent claims of a patent to be sure I don't infringe the patent? Does this apply to US, Europe and other countries?

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  • It you find one of the answers acceptable, it would be helpful for you to accept it by clicking the check mark.
    – Eric S
    Apr 21 at 14:24

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In theory, you do not infringe a patent based on the scope of a dependent claim if you do not infringe the patent based on the scope of a respective independent claim.

In practice, it is possible to find granted patents in which the dependent claims undo a feature of a claim it depends upon and adds a different feature, they are sometimes called false dependent claims. In that case, you might infringe the patent based on the scope of a dependent claim but not of its independent claim.

Sometimes the patent law does not correctly specify that the dependent claims include all features of the claim they depend upon. The defendant could argue that, in theory, a dependent claim shall include all the features of the claim it depends upon, but what the outcome of that may be is unclear. It is not reassuring that the dependent claim, by definition, shall be more limited than the independent claim when you see granted patents with that type of claims: they are granted and they are problematic due to the uncertainty they produce. Reviewing the dependent claims to check if there are no false dependent claims is advisable.

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  • I would never have thought a “false” dependent claim could get through, are there circumstances that are more likely to cause it, like multiply dependent?
    – George White
    Apr 21 at 21:03
  • This happens in the EPO ??
    – George White
    Apr 21 at 21:58
  • @GeorgeWhite Sometimes at the EPO, yes, but I have come across this situation more frequently in national patents. Multiple dependence does not seem to cause it. Sometimes it is due to examiners, patent attorneys or being are inexperienced. Sometimes experienced attorneys try to protect more with this kind of tricks. Apr 22 at 6:58
  • @GeorgeWhite The main reason why this gets through, and this is acknowledged by examiners, is that examiners do not put much effort in the examination of dependent claims, so if the independent claims are deemed patentable, most of the times they skim through the dependents, if nothing catches their eye in that quick review, they grant the patent and move on to another file. Apr 22 at 7:01
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If you mean that your art mismatches the independent claim on which the dependent claim overtly calls out as its independent claim, then under all WIPO-signatory nations (and certainly the USA), your art does not infringe the dependent claim because it does not infringe the independent claim as well. Each dependent claim is an implied logical-AND extension of the independent claim that the dependent claim overtly calls out as its basis. Your work does not satisfy the logical-AND there, hence no possibility of infringement.

This assumes that the court & jury (e.g., in the USA) agree with your self conclusion that your work mismatches the independent claim on which the dependent claim depends. Perhaps you are over-confident due to yearning for a particular outcome. To forestall that overconfidence, you should consult with a patent attorney to see if the patent attorney likewise as a rather neutral party also agrees that your work is a total mismatch to the metes & bounds carved out by the independent claim that is called out by the dependent claim that partially matches your work.

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  • Good answer except “mismatch” might be misunderstood. In order to infringe a claim your product or activity needs to do or have everything positively required in a claim.
    – George White
    Apr 20 at 19:08
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By definition, in all countries, dependent claims are a narrowing of independent claims. If you do not infringe an independent claim you cannot infringe a claim that depends from it. Period.

However, an independent claim might be hard to understand and apply to the alleged infringing product. A dependent claim might add limitations that make it more clear what the invention is and therefore make a jury see more clearly that you infringe.

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