～ざるを得ない cannot avoid, have no choice but

「どうしても～する必要がある・～しなければならない」
cannot avoid; have no choice but to

Used when the situation cannot be avoided even though the person involved does not want to do the action. ざる is an old term meaning ない　The pattern ざるをえない　has a stronger sense of compulsion, must do even though doesnt want to than ないわけにはいかない (no way not to do).

（１）会社の上の人に命令された仕事なら、社員はいやでもやらざるをえない。
If this is a job ordered by more senior people in the company, even if the staff don't like it they have to do it.

（２）会社が倒産したのは社長に責任があると言わざるをえない。
We have to say that the President was repsonsible for the bankruptcy of the company.

（３）化学は好きではないが、必修だから取らざるをえない。
I dont like Chemistry, but its a compulsory study so I have to take it.

（４）体調はあまりよくないが、今日は人手が足りないので働かざるをえない。
My body is not so good, but today there are not enough people so I have to work.

（５）みんなで決めた規則だから、守らざるを得ない。
Because this was a rule that was decided together, we have to respect it.

（６）原料がどんどん値上がりしているのですから、製品も値上げせざるを得ない。
Because the price of the original ingredients is going up, we have to put up the price of the products.

（７）彼は登山中に消息不明となり、すでに５年経っている。死んだと考えざるを得ない。
He disappeared during his mountain climb and already five years have passed, so we have to think that he died.

（８）こんなにひどい雨では運動会は中止せざるを得ない。
In this awful rain we have to cancel the athletic meet.