expression
by all rights; properly speaking; legally speaking
Used to state what should be the case according to rules, norms, or expectations, often followed by a contrast with reality. Can imply a legal or formal standard, but also used in everyday reasoning.
本来であれば、今日中に報告書を提出しなければならない。
By all rights, I should submit the report by the end of today.
本来であれば彼が責任を取るべきだが、誰もそうは言わなかった。
Properly speaking, he should take responsibility, but no one said so.
Combination of 本来 (ほんらい, 'originally, essentially') and the conditional form であれば of the copula である, literally 'if it is originally/essentially'.