I’ve been reading about the doctrine of equivalents, it is said that a product/process is said to be infringed under doctrine of equivalents if the substitute element of the accused product/process matches the function, way and result of the claimed element.

From the example below would Competitor B infringe the method/process of Competitor A under the doctrine of equivalents?

Competitor A

A method comprising:

A) Obtaining an electrical circuit

B) Converting AC to DC

C) Illuminating a LED

Competitor B

A method comprising:

A) Obtaining an electrical circuit

B) Illuminating a AC LED directly out of the AC line voltage

  • Does the “AC LED” internally convert the AC to DC?
    – Eric S
    Oct 2, 2021 at 12:46
  • No the AC LED does not convert the AC to DC, it operates directly out of AC line voltage
    – Dan21
    Oct 2, 2021 at 13:58
  • A true AC LED would be a very esoteric device so I’d guess that no infringement would occur. I’m not an expert however so I’ll leave it to others to answer.
    – Eric S
    Oct 2, 2021 at 14:04

1 Answer 1


I don’t think so. In your example a step is eliminated. That is nothing like substituting an equivalent step for a literal step.

This a US view. There is a good Wikipedia entry on DOE that shows it is very different in other locations.

In the US the criteria is

  1. Performs substantially the same function 2. In substantially the same way 3. To obtain the same result

A recent case involved the issue of is salt the same as dissolved salt. It is getting rarer for a DOE argument to win in the US courts.

  • Thank you George for you answer it’s very much appreciated!
    – Dan21
    Oct 3, 2021 at 11:52
  • Actually, it might not be that easy. If we look at steps b) and c) together, they equate to "lighting a dc led and doing the necessary electrical stuff". If now an ac led would be found to be equivalent to the dc led, then step b) of the competitor would also be lighting an, albeit ac, led. However, I don't think it's possible to find an answer to this question - it simply depends on the specifics. The above is just an example of how even apparently simple substitutions can be quite complicated.
    – user18033
    Oct 3, 2021 at 17:46
  • I edited my answer
    – George White
    Oct 3, 2021 at 21:20

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