Technical Points on Patent Claim Drafting

1. It must always be remembered that a claim will be examined, and possibly also opposed/litigated, in many different territories, each having different criteria for validity and infringement.  Whilst there are of course many similarities between different Patent Offices, one needs to think about patent practice outside the territory in which one is based.  This will be particularly relevant when considering claim language for inventions relating to therapy and diagnosis, and perhaps also to situations where a doctrine of equivalents may be applicable.

2. A patent claim should be as clear as possible, and if there are any potentially ambiguous terms definitions of them should be provided in the specification, with the aid of numerical ranges if appropriate.  If, for example, a person is defined in a claim as being a non-smoker, think about whether it would be useful to define non-smokers as having had less than 10 cigarettes in the preceding year.  Clearly features which will be important in distinguishing over the prior art will need to be looked at carefully.  Many Patent Offices (including the EPO and USPTO) are strict on clarity.

3.  A common mistake is for method claims to refer to too many steps, making it less likely that any single party will carry out each step.  For example, taking the following claim:

A method of turning copper into gold comprising:

– heating the copper to 55⁰C, and

-transmuting the copper to gold.

It could be shortened to:

A method of turning copper into gold comprising:

–          transmuting copper which has been heated to 55⁰C.

Thus method claims should be reviewed to see whether any steps can be taken out in this way, which effectively increase their breadth thus providing better protection.

4.  There may be advantages to adding steps to dependent method claims so that they extend to making the commercial product.  Normally the protection afforded to method claims will also cover the direct product of the method.

5.  Don’t make the assumption that long method claims where different steps will be carried out by different parties are worthless.  In some territories, such as the US, these claims may provide useful protection, where for example inducement to infringement can be shown.

6. Whether or not the preamble of a claim is limiting seems to be an open question in many territories.  In the US case there is case law to support both positions. Claims should be drafted thoughtfully with this in mind.

7. Don’t have too many claims.  In many territories this will lead to an increase in costs.  Whilst in many cases claim number can be reduced at regional/national phasing, in some territories that will not lead to a decrease in claims fees.

8. Make sure you have method claims that are equivalent to the use claims that may be present.  Use claims not allowable in certain territories, such as the US, and so in such territories you will need to rely on method claims.


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