Refers to the attitude or principle of acting based on what is convenient or advantageous at the moment, often without regard for principles or long-term consequences.
His actions are nothing but opportunism.
That policy is based on expediency.
日和見主義 emphasizes waiting to see which way the wind blows before acting, while 便宜主義 focuses more on choosing the most convenient or advantageous course at the moment.
principle of discretionary prosecution; principle of opportunity
Compound of 便宜 (convenience, expediency) and 主義 (principle, doctrine).