そうでなければ

expression

otherwise; or else; if not

Used to introduce the consequence or alternative when a preceding condition is not met. Often at the beginning of a sentence or clause.

• 急いそいでください。そうでなければ遅おくれますよ。

  Please hurry. Otherwise, you'll be late.

• 彼かれは来くるかもしれない。そうでなければ電でん話わがあるはずだ。

  He might come. If not, there should be a phone call.