The rules adopted by WIPO about drawings are quite restrictive. Only black lines, no colours and so on. But how strict are the officers when they evaluate them? Would s drawing made with a simple diagram tool instead of complex CAD raise some eyebrows? It will respect the proportions as required, but it will be less accurate and the geometric figures will be far from perfect.

It might also have lines of different thickness, for example it could use a thick line to represent a steel beam and a thin line to represent a guy wire. But rule 11.13 (a) states:

Drawings shall be executed in durable, black, sufficiently dense and dark, uniformly thick and well-defined, lines and strokes without colorings.

Will this invalidate the drawing?

1 Answer 1


The PCT process is strict about drawings, much more so than the national USPTO process. If you are lucky when you get "an invitation to correct defects" you will be able to fix the drawings without being seen as "adding new matter".

As long as the lines are legible you will probably be able to replace drawings with other drawings that do follow the rules. Note that the rules cover many other aspects of drawings, not just line width. I have seen one case of thin pencil lines completely disappearing in the scan the office does when filing by paper, resulting in a blank drawing page.

There are free programs for making drawings and you can even do it the way it was done before computers could help with producing drawings.

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    I agree with you. In PCT applications they are quite strict. It is a common strategy to file an EP patent application as priority application, get the European Search Report, and then file a PCT with the same files claiming priority from the EP and withdrawing the priority application. Oftentimes we receive formal office actions in the PCT, not in the EP, about the drawings. Sep 3, 2022 at 13:38

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