He vowed to take legal action.

他发誓要诉诸法律行动。

One possible solution, if all else fails, is to take legal action.

如果其他方案都不行，一个可能的解决办法就是提起诉讼。

He plans to take legal action.

他打算为此采取法律行动。

If you do not pay up, I'll take legal action.

你若不将钱还清的话，我全采取法律行动的。

She threatened to take legal action against the hospital.

她威胁说要把医院告上法庭。