if, as and when

Adverb

as and when informal not-comparable

(informal, chiefly law) In the event that the thing being discussed comes to pass.

Japanese Meaning

議論されている事柄が実際に生じた場合、特に法律上の非公式な文脈で用いられる表現

We will provide further instructions if, as and when the need arises.

必要が生じた場合には、追加の指示を出します。

Sense（1）

(informal, chiefly law) In the event that the thing being discussed comes to pass.

（ canonical ）