Document ID: ./input/supremecourt_opinions/opinions/boundvolumes/524bv.pdf
Page Number: 698.0

524US2

Unit: $U96

[09-15-00 14:39:49] PAGES PGT: OPIN

Cite as: 524 U. S. 624 (1998)

653

Opinion of the Court

issue of material fact. Evidence which was merely colorable
or not signiﬁcantly probative would not have been sufﬁcient.
Anderson v. Liberty Lobby, Inc., 477 U. S. 242, 249–250
(1986).

We acknowledge the presence of other evidence in the rec-
ord before the Court of Appeals which, subject to further
arguments and examination, might support afﬁrmance of the
trial court’s ruling. For instance, the record contains sub-
stantial testimony from numerous health experts indicating
that it is safe to treat patients infected with HIV in dental
ofﬁces. App. 66–68, 88–90, 264–266, 268. We are unable to
determine the import of this evidence, however. The record
does not disclose whether the expert testimony submitted by
respondent turned on evidence available in September 1994.
See id., at 69–70 (expert testimony relied in part on materi-
als published after September 1994).

There are reasons to doubt whether petitioner advanced
evidence sufﬁcient to raise a triable issue of fact on the
signiﬁcance of the risk. Petitioner relied on two principal
points: First, he asserted that the use of high-speed drills
and surface cooling with water created a risk of airborne
HIV transmission. The study on which petitioner relied
was inconclusive, however, determining only that “[f]urther
work is required to determine whether such a risk exists.”
Johnson & Robinson, Human Immunodeﬁciency Virus-1
(HIV–1) in the Vapors of Surgical Power Instruments, 33 J.
of Medical Virology 47 (1991). Petitioner’s expert witness
conceded, moreover, that no evidence suggested the spray
could transmit HIV. His opinion on airborne risk was based
on the absence of contrary evidence, not on positive data.
App. 166. Scientiﬁc evidence and expert testimony must
have a traceable, analytical basis in objective fact before it
may be considered on summary judgment. See General
Electric Co. v. Joiner, 522 U. S. 136, 144–145, 146 (1997).
Second, petitioner argues that, as of September 1994, CDC
had identiﬁed seven dental workers with possible occupa-