[John Jamieson]

Blue paint under the fingernails, or on the car bumpers, or both?

[Rheo]

Strange huh?...can't imagine the defense TRYING to place painted bumpers in DW's house so it matches the blue paint under her fingernails.

Can't figure out what it means.

[Valpal1]

Some one asked about impeached testimony or impeaching witnesses. Sorry if its been answered.

2: to cast doubt on: as

a: to attack the validity of (a judgment or verdict) because of judicial or
juror misconduct

b: to challenge the credibility of (a witness) or the validity of (a witness's
testimony)
Example: a witness, including a criminal defendant who testifies in his own
behalf, may be impeached on the ground of former conviction -- W. R.
LaFave and A. W. Scott, Jr.
(see also impeachment evidence at evidence)
(compare rehabilitate)
Note: A witness may be impeached by character evidence or
circumstantial evidence relating to the credibility of the witness, and esp.
on the grounds of prior convictions, prior inconsistent statements,
contradiction by other evidence, and the witness's reputation for truth,
prior acts of misconduct, and partiality.

It's not like the testimony is thrown out, just that it can be used by the jury in weighing the validity of testimony as they consider and make a decision.