-Just when a scientific principle or discovery crosses the line
between the experimental and demonstrable stages is difficult to
define.  Somewhere in this twilight zone the evidential force of the
principle must be recognized, and while courts will go a long way in
admitting expert testimony deduced from a well-recognized scientific
principle or discovery, the thing from which the deduction is made
must be sufficiently established to have gained general acceptance in
the particular field in which it belongs.- 54 App. D.C., at 47, 293
F., at 1014 (emphasis added). Because the deception test had -not yet
gained such standing and scientific recognition among physiological
and psychological authorities as would justify the courts in admitting
expert testimony deduced from the discovery, development, and
experiments thus far made,-evidence of its results was ruled
inadmissible.  Ibid.  The merits of the Frye test have been much
debated, and scholarship on its proper scope and application is
legion.  Petitioners' primary attack, however, is not on the content
but on the continuing authority of the rule.  They contend that the
Frye test was superseded by the adoption of the Federal Rules of
Evidence.  We agree.
  We interpret the legislatively-enacted Federal Rules of Evidence as
we would any statute.  Beech Aircraft Corp. v. Rainey, 488 U. S. 153,
163 (1988).  Rule 402 provides the baseline:
      -All relevant evidence is admissible, except as otherwise
provided by the Constitution of the United States, by Act of Congress,
by these rules, or by other rules prescribed by the Supreme Court
pursuant to statutory authority.  Evidence which is not relevant is
not admissible.
--Relevant evidence- is defined as that which has -any tendency to
make the existence of any fact that is of consequence to the
determination of the action more probable or less probable than it
would be without the evidence.-  Rule 401.  The Rule's basic standard
of relevance thus is a liberal one.
  Frye, of course, predated the Rules by half a century.  In United
States v. Abel, 469 U. S. 45 (1984), we considered the pertinence of
background common law in interpreting the Rules of Evidence.  We noted
that the Rules occupy the field, id., at 49, but, quoting Professor
Cleary, the Reporter, explained that the common law nevertheless could
serve as an aid to their application:
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