noun
lack of evidence; insufficient evidence
Used in legal, formal, or investigative contexts to state that the evidence is not enough to prove something.
証拠不十分のため、容疑者は釈放された。
The suspect was released due to insufficient evidence.
裁判官は証拠不十分として訴えを棄却した。
The judge dismissed the case for lack of evidence.
証拠不足 is a more common and slightly less formal synonym, also meaning insufficient evidence.
Compound of 証拠 (evidence) and 不十分 (insufficient).