Halliburton Oil Well Cementing Co. v. Walker

Background

A patent owner, who licensed a device for measuring depth in oil wells by timing pressure or sound echoes, sued an oil-field services company for infringing that patent. The lower courts found the patent claims valid and that the company infringed. The patentee’s alleged improvement added a short tuned tube (an acoustical resonator) meant to make repeating pipe-shoulder echoes easier to see on a recording.

Reasoning

The Court focused on whether the patent’s claims met the statutory requirement to describe an invention in "full, clear, concise, and exact" terms (Rev. Stat. 4888). It found the key claims described the resonator only by what it does — a functional “means” to tune and distinguish echoes — and did not describe the resonator’s physical structure or how it fit into the machine. Because the patent combined old parts, the Court said combination patents must still show the structure and arrangement of the new part. The Court therefore held those claims indefinite and invalid, reversed the lower courts’ rulings, and refused to let a vague functional claim give the patentee a blanket right to block other methods that perform the same job.

Real world impact

The decision removes broad power from the patent owner to exclude any device that performs the echo-filtering function, including electric filters like the accused device. It stresses that inventors who add known parts to old combinations must clearly describe the parts and how they work together, or else lose coverage for vague functional language.

Dissents or concurrances

One Justice agreed with the invalidity ruling but reserved judgment on special issues for combination patents; another Justice dissented from the Court’s disposition.