IP-Managers in large international companies often find that the grant rates of their patents are significantly higher in their own jurisdiction than in other jurisdictions. One of the reasons for this effect is that the patent applications are drafted taking into account the requirements of only one jurisdiction.

Drafting patent applications is a challenging task anyway, but it becomes even more difficult if the requirements of different jurisdictions should be considered. A drafting style working for one jurisdiction may cause major problems in other jurisdictions. Many problems could be avoided if they were considered at the drafting stage.

I will show periodically examples of problems caused by drafting or prosecution weaknesses resulting in rejections or narrow claims. The examples are taken from real cases, with the original wording changed to focus only on the key issue.

Today´s example relates to: External Parameters used for defining Claim Features

Example claim:

“A reflector with an operating wavelength…comprising:

a layer having a thickness of less than the operating wavelength.”


The claimed range of layer thicknesses depends on the wavelength at which the reflector is operated. Although a real reflector is optimized for a particular wavelength by selecting the appropriate layer thickness, the operating wavelength can be any wavelength from the perspective of the patent application. Consequently, the thickness of the layer can be arbitrary, and the claimed feature does not limit the scope of the claim as intended.

In some jurisdictions (e.g. at the EPO), it might even be difficult to remove such a feature from the independent claim, even if other definitions would be available to limit the scope of the claim.

So the question is: How can such a situation be avoided?


Since the target application and the corresponding operating wavelength range are usually known, it would be easy to calculate a corresponding thickness range of the layer. This thickness range can be claimed, which would avoid reference to an external parameter.


Take care when defining structural features by parameters external to the claimed device. The claim might not get limited in the intended way. Try to find a way to break down the external parameter to internal parameters.

In order to achieve high grant rates and broad scope of protection in all relevant jurisdictions, IP-Managers should take care that the requirements of all these jurisdictions are considered by their drafting attorneys at the drafting stage.

Drafting guidelines are a good way of ensuring high-quality applications that are suitable for all jurisdictions relevant to a company.

About the blogpost author:

Stefan Müller is partner at 2SPL PartG mbB since 2012 and an expert for the protection of digital solutions in Europe. Before becoming a patent attorney, he studied physics and gained practical experience in the semiconductor industry.

Feel free to connect with him on LinkedIn.