Patent claims are written to “particularly point out and distinctly claim” an invention in a statutory class. The prescribed and accepted way of writing a claim is that each claim shall be a single sentence. That is, the standard custom as to claim construction is that each claim must be the object of a single sentence, however long. This requirement of a single sentence may sometimes be troublesome in long, complicated claims with many elements, sub-elements, and intricate relationships between elements.
Most of the patent office prescribe that the claims in a patent application begins with a standard introductory phrase such as “I [or We] claim,” “The invention claimed is,” or the equivalent. In a patent application with more than one claim, the introductory phrase, such as “I claim,” appears only once, i.e., before the first claim.
Standard Office practice also insist that each claim begin with a capital or upper-case letter and end with a period, so that each claim reads as a complete sentence when taken with the introductory words, for example, “I claim,” “We claim,” “The invention claimed is,” or “What is claimed is,” or the equivalent language. It may be understood that except for standard capitalization such as for units like °C., no other capital letters may appear in the body of the claim.
In connection with the single-sentence rules as described above, it is important to watch grammar, particularly verb forms, to make sure the claim reads as a complete sentence. For example, “I claim: A machine comprises . . . [parts A and B]” does not form a complete sentence. However, the generally standard phraseology, “I claim: A machine comprising . . . [parts A and B]” does form a sentence.
The claim drafter should also select a verb form, for example, participle (“-ing”), or third person (“-s”), and use it consistently throughout each entire claim. Also, where possible, the verb form in a claim is preferably in the present tense, unless a past or future event is being described.