The inventor must also demonstrate the capacity of the invention to achieve its intended purpose. Scott v. Finney, 34 F.3d 1058, 1062 (Fed. Cir. 1994). Cordis first points to BSC's concession at the interference trial that Cordis had actually reduced to practice on September 14, 1993 as evidence of that fact.

The degree and nature of testing required for a reduction to practice necessarily depends upon the nature and purpose of the invention at issue. Scott v. Finney, 34 F.3d 1058, 1061-63, 32 U.S.P.Q.2d 1115, 1118-19 (Fed. Cir. 1994). For example, mere construction of a prototype may be enough to qualify as a reduction to practice in those rare instances where a device is so simple in nature that satisfactory operation is obvious even without testing.

Whether testing is necessary to determine an invention works for its intended purpose and whether a given test method is sufficient are questions of fact. Barry v. Medtronic, Inc., 914 F.3d 1310, 1322 (Fed. Cir. 2019); z4 Techs., Inc. v. Microsoft Corp., 507 F.3d 1340, 1349 (Fed. Cir. 2007); see also Scott v. Finney, 34 F.3d 1058, 1061 (Fed. Cir. 1994) ("[T]he testing requirement depends on the particular facts of each case, with the court guided by a common[-]sense approach in weighing the sufficiency of the testing."). Weighing evidence and performing factfinding at summary judgment "is an inappropriate exercise, at either the appellate or the district court level."

The inventor need show only that the invention is 'suitable' for its intended use." Scott v. Finney, 34 F.3d 1058, 1062-63 (Fed. Cir. 1994). "It is not necessary for testing to have proceeded to the point where the device is ready for commercialization in order to have an actual reduction to practice."

Travis v. Baker, 137 F.3d 109, 111 (CCPA 1943); Hybritech, 802 F.2d 1367, 1376 (Fed. Cir. 1986). Whereas, an actual reduction to practice must show that the invention works for its intended purpose in the actual environment of its use. Scott v. Finney, 34 F.3d 1058, 1062 (Fed. Cir. 1994). In Scott, the Court explained:

Reduction to practice does not, however, require that the invention "be in a commercially satisfactory stage of development." Scott v. Finney, 34 F.3d 1058, 1061 (Fed. Cir. 1994); see also Skycam, LLC v. Bennett, 900 F. Supp. 2d 1264, 1278 (N.D. Okla. 2012); Diodem, LLC v. Lumenis Inc., No. CV03-2142 GAF (RCx), 2005 WL 6225364, at *4 (C.D. Cal. Sept. 15, 2005). Moreover, an inventor need not demonstrate successful testing on humans to reduce to practice an invention ultimately intended for human use.

Thus, while "[i]t is not necessary for testing to have proceeded to the point where the device is ready for commercialization in order to have an actual reduction to practice, . . . there must be a relationship between the test conditions and the intended functional setting . . . and the tests must prove that the invention will perform satisfactorily in the intended functional setting." Koval v. Bodenschatz, 463 F.2d 442, 447 (C.C.P.A. 1972); accord Scott v. Finney, 34 F.3d 1058, 1061 (Fed. Cir. 1994) ("Reduction to practice does not require that the invention, when tested, be in a commercially satisfactory stage of development."). Accordingly, "[t]esting need not show utility beyond a possibility of failure," but it must show "utility beyond a probability of failure."

An actual reduction to practice occurs when the inventor: (1) constructs a product that is within the scope of the claimed invention, and (2) demonstrates that his invention actually worked for its intended purpose. Scott v. Finney, 34 F.3d 1058, 1062-63 (Fed. Cir. 1994). See also Cooper v. Goldfarb, 154 F.3d at 1327; Estee Lauder Inc. v. L'Oreal S.A., 129 F.3d 588, 593 (Fed. Cir. 1997); UMC Elecs. Co. v. United States, 816 F.2d 647, 652 (Fed. Cir. 1987).

As for Taskett's argument that Dentlinger did not prove reduction to practice because he did not show that he "determined that the invention would work for its intended purpose," Cooper, 154 F.3d at 1327, we agree with the Board that to meet this requirement, the test need not occur under conditions of actual, commercial use. See Scott v. Finney, 34 F.3d 1058, 1063 (Fed. Cir. 1994) ("In tests showing the invention's solution of a problem, the courts have not required commercial perfection nor absolute replication of the circumstances of the invention's ultimate use. . . . [Although,] more scrupulous testing [is prescribed] under circumstances approaching actual use when the problem includes many uncertainties."). Nothing in Eaton or Newkirk is to the contrary.

In reaching that conclusion, the PTO Board once again relied on Kinney's testimony and laboratory notebook, which illustrated that the TD01 successfully stored data following a read-write-read operation. Cognizant that the TD01 was tested with an oscilloscope rather than a sense amplifier, the PTO Board, relying on Scott v. Finney, 34 F.3d 1058, 32 USPQ2d 1115 (Fed. Cir. 1994), found that Evans reduced the count to practice because the test results established a reasonable expectation that the TD01 would operate for its intended purpose. . . . Finally, the PTO Board addressed Eaton's case for priority by assuming that he was entitled to February 12, 1987 — the date he filed his application — as his date of constructive reduction to practice.