How does the transitional phrase “composed of” compare to “consisting of” in patent claims?

How does the transitional phrase “composed of” compare to “consisting of” in patent claims?

The transitional phrase “composed of” is generally treated similarly to “consisting of” in patent claims, but with some nuances:

• Similar to “consisting of”: “Composed of” is typically interpreted as a closed transition, excluding unrecited elements.
• Potential flexibility: In some cases, “composed of” might be interpreted more flexibly than “consisting of,” depending on the context and specification.

According to MPEP 2111.03:

“The transitional phrase ‘composed of’ has been interpreted in the same manner as either ‘consisting of’ or ‘consisting essentially of,’ depending on the facts of the particular case.“

While “composed of” is generally treated as a closed transition like “consisting of,” its interpretation can depend on the specific circumstances of the case. Examiners and practitioners should carefully consider the context and specification when interpreting claims using “composed of” as a transitional phrase.

To learn more:

• transitional phrases
• composed of
• consisting of
• claim interpretation
• closed transition