Goodrich Tire Co., 114 F.3d 851, 853 (9th Cir. 1997); see also Daubert I, 509 U.S. at 590 (noting that expert testimony based on mere “subjective belief or unsupported speculation” is inadmissible). We cannot say the district court abused its discretion when it barred Schiff and Parker from testifying at trial after finding their testimony to be “inherently unreliable and unsupported by the facts.” The district court properly exercised its “gatekeeping role” under Daubert I, 509 U.S. at 597.
B
We next address the exclusion of fact witnesses. The general issue is whether witnesses not listed in Rule 26(a) disclosures—and who were identified 15 months after the discovery cutoff and only ten months before trial—were identified too late in the process.
The Federal Rules of Civil Procedure require parties to provide to other parties “the name … of each individual likely to have discoverable information—along with the subjects of that information—that the disclosing party may use to support its claims or defenses.” Fed. R. Civ. P. 26(a)(1)(A)(i). And “[a] party who has made a disclosure under Rule 26(a) … must supplement or correct its disclosure” in a “timely manner if the party learns that in some material respect the disclosure … is incomplete or incorrect, and if the additional or corrective information has not otherwise been made known to the other parties during the discovery process or in writing.” Id. R. 26(e). A party that does not timely identify a witness under Rule 26 may not use that witness to supply evidence at a trial “unless the failure was substantially justified or is harmless.” Id. R. 37(c)(1); see also Yeti by Molly, 259 F.3d at 1105. Indeed,
