with good reason

Based on sound judgment and reasonable inference; with one's proper justifications; on good grounds.

Japanese Meaning

合理的な根拠に基づいて / 正当な理由により / 妥当な理由があって

She refused the invitation with good reason, having discovered the organizer's history of unreliable behavior.

彼女は主催者がこれまでに信頼できない行動をしてきたことを知っていたため、もっともな理由があって招待を断った。

Sense（1）

Based on sound judgment and reasonable inference; with one's proper justifications; on good grounds.