だとif it's the case

明日(あした)が雨(あめ)だと傘(かさ)が必要(ひつよう)になります。

If it's the case that it will rain tomorrow, you'll need an umbrella.

刑事(けいじ)：「この証拠(しょうこ)がでっちあげだと我々(われわれ)は不利(ふり)になる…。」

Detective: 'If it's the case that this evidence was fabricated, we're at a disadvantage...'

独(ひと)り言(ごと)：「来週(らいしゅう)の月曜日(げつようび)も祝日(しゅくじつ)だと三(さん)連休(れんきゅう)になるのになぁ〜。」

Monologue: 'If it's the case that next Monday is a holiday too, we’d have a three-day weekend...'

有名(ゆうめい)な研究(けんきゅう)者(しゃ)であれ、半(はん)世紀(せいき)前(まえ)だとこの理論(りろん)は世間(せけん)に受(う)け入(い)れられないだろう。

Even if it's the case that the researcher is well-known, this theory probably wouldn't have been accepted by the public half a century ago.

監督(かんとく)：「あの涙(なみだ)が演技(えんぎ)だと、彼(かれ)は才能(さいのう)のある役者(やくしゃ)だ。ぜひスカウトさせてもらおう！」

Director: 'If it's the case that those tears were acting, then he's a truly gifted actor. I definitely want to scout him!'