463 Mass. 353 - Appellee Commonwealth Brief - Mass Cases

Fifth Amendment violation can be harmless if "the
beneficiary of a constitutional error ... prove[s]
beyond a reasonable doubt that the error complained of
did not contribute to the verdict obtained." The Court
expressed the harmless standard as whether there is "a
reasonable possibility that the evidence complained of
might have contributed to the conviction." Id., at 23,
quoting Fahy v. Connecticut, 375 U.S. 85, 86-87 (1963)
Almost twenty years later, in Delaware v. Van
Arsdall, 475 U.S. 673, 684 (1986), the Supreme Court
affirmed that "the constitutionally improper denial of
a defendant's opportunity to impeach a witness for
bias, like other Confrontation Clause errors, is
subject to Chapman harmless-error analysis" and set out
certain "factors" that might be applicable in a denial
of the right to impeach for bias case:
Whether such an error is harmless in a
particular case depends upon a host of
factors, all readily accessible to reviewing
courts. These factors include the importance
of the witness' testimony in the
prosecution's case, whether the testimony was
cumulative, the presence or absence of
evidence corroborating or contradicting the
testimony of the witness on material points,
the extent of cross-examination otherwise
permitted, and, of course, the overall
strength of the prosecution's case.
VanArsdall, 475 U.S. at 684.
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