～にしろ／～にせよ — Whether One Way or Another

理由が何であるにせよ、遅刻は許されない。

Riyuu ga nan de aru ni seyo, chikoku wa yurusarenai.

Whatever the reason may be, being late is not acceptable.

Concedes any possible reason; the conclusion holds regardless

行くにしろ行かないにしろ、返事だけはしなさい。

Iku ni shiro ikanai ni shiro, henji dake wa shinasai.

Whether you go or not, at least give a reply.

Paired にしろ...にしろ lists both alternatives

冗談にせよ、言っていいことと悪いことがある。

Joudan ni seyo, itte ii koto to warui koto ga aru.

Even if it's a joke, there are things you should and shouldn't say.

Noun 冗談 + にせよ concedes the 'joke' framing but still objects