そんなことはしないでしょう

wouldn't do such a thing

→ そんな
phrase Rare #24,957
wouldn't do such a thing Often used to make a supposition or describe what someone would do in a hypothetical situation. The subject is understood from context.
JA: 私なら、そんなことはしないでしょう。
EN: If it were me, I wouldn't do that.

日本人ならそんなことはしないでしょう。

A Japanese person wouldn’t do such a thing, would they?

私なら、そんなことはしないでしょう。

If it were me, I probably wouldn't do that.

紳士であれば、そんなことはしないでしょう。

A gentleman wouldn't do such a thing.