Chapter §2.03 Dependent Patent Claims

• Jurisdiction: United States

§2.03 Dependent Patent Claims

Patent claims are drafted in either independent or dependent form. A dependent claim is one that refers to (or depends from) some other, previously presented claim, whereas an independent claim stands alone without referring to any other claim. A dependent claim includes (i.e., incorporates by reference) all limitations of the claim from which it depends, and also adds some further limitation(s). Thus, use of the dependent form of claiming is merely a shorthand way of repeating all the limitations of some other claim while adding some additional limitation(s).

For example, consider the following example patent claims:

1. A ceiling fan comprising a plurality of blades connected to a rod attached to a motor.

2. The ceiling fan of claim 1 wherein said rod is hollow.

Claim 2 is drawn to a fan having all the elements recited in claim 1 plus the additional limitation that the rod element is hollow. Thus the scope of claim 2 is narrower than claim 1; claim 1 is not limited to rods that are hollow.¹³⁵ Claim 2 could be rewritten in independent form to read:

2. A ceiling fan comprising a plurality of blades connected to a rod attached to a motor, wherein said rod is hollow.

The two versions of claim 2 presented above are identical in their coverage. The first version of claim 2, written in dependent form, is simply a shorthand method of stating the claim in a way that requires fewer words. If every claim of a patent were written in independent form, patent specifications would become unacceptably long.

[A] Statutory Basis: 35 U.S.C. §§112(c)-(e)

Dependent claiming principles are governed by the following paragraphs of 35 U.S.C. §112:

(c) Form.—A claim may be written in independent or, if the nature of the case admits, in dependent or multiple dependent form.

(d) Reference in Dependent Forms.—Subject to subsection (e), a claim in dependent form shall contain a reference to a claim previously set forth and then specify a further limitation of the subject matter claimed. A claim in dependent form shall be construed to incorporate by reference all the limitations of the claim to which it refers. ¹³⁶

[B] Claim Groupings

Although a patent application need only include one claim, most applications contain more. Claims are typically presented in a patent application in groups. For purposes of illustration, consider a patent application claiming "a widget comprising A, B, and C." Further assume that the patent application presents 20 claims, which contain two independent claims and 18 dependent claims, arranged as shown in Figure 2-4.

FIGURE 2-4. Example Claim Groupings

This typical claiming structure can be visualized as two inverted pyramids that represent the variation in scope of the claims from broadest to narrowest, as depicted in Figure 2-5.

FIGURE 2-5. Scope Representation for Example Claim Groupings of Figure 2-4

[C] Multiple Dependent Claims

Paragraph (e) of 35 U.S.C. §112 provides:

(e) Reference in Multiple Dependent Form.—A claim in multiple dependent form shall contain a reference, in the alternative only, to more than one claim previously set forth and then specify a further limitation of the subject matter claimed. A multiple dependent claim shall not serve as a basis for any other multiple dependent claim. A multiple dependent claim shall be construed to incorporate by reference all the limitations of the particular claim in relation to which it is being considered. ¹³⁷

U.S. claiming practice allows the use of multiple dependent claims. In accordance with 35 U.S.C. §112(e), a claim in multiple dependent form must depend from two or more previously set forth claims. The dependency must be phrased in the alternative, that is, with an "or" rather than an "and." For example, the following multiple dependent claims are proper:

5. The widget according to claims 3 or 4, further comprising a pulley.

5. The widget as in any one of claims 1–4, in which said lever arm comprises steel.

However, the following claims are improper:

5. The widget according to claims 3 and 4, further comprising a pulley.

5. The widget as in claims 1–4, in which said lever arm comprises steel.

The statute prohibits the inclusion of a multiple dependent claim that depends from another multiple dependent claim. Consider the following example:

3. The widget of claim 2, further comprising a spring.

4. The widget of claim 3, in which said spring is helical.

5. The widget according to claims 3 or 4, further comprising a pulley.

6. The widget of claim 4 or 5, further comprising a lever arm.

Claim 6 in the above example is improper, because it is multiply dependent and one of the two claims it depends from, claim 5, is...