Translation

疑いを差し挟む / 非難する / 攻撃する

Meaning

Impugn means to attack or call into question someone's honesty, motives, character, or the truth of a claim. It is formal and often used with integrity or credibility.

Examples

• その発言は彼女の誠実さを疑うものでした。
  The remark impugned her integrity.
• 弁護士は証人の信用性を攻撃しようとしました。
  The lawyer tried to impugn the witness's credibility.