にせよ〜にせよ— Whichever the Case

• 行くにせよ行かないにせよ、早く決めてください。

  Iku ni seyo ikanai ni seyo, hayaku kimete kudasai.

  Whether you go or not, please decide quickly.

  Two opposite verbs (行く／行かない) framed by にせよ〜にせよ; the request holds in either case

• 賛成にせよ反対にせよ、意見を述べるべきだ。

  Sansei ni seyo hantai ni seyo, iken wo noberu beki da.

  Whether for or against, you should state your opinion.

  Nouns 賛成／反対 attach directly to にせよ

• 電話にしろメールにしろ、必ず連絡してね。

  Denwa ni shiro meeru ni shiro, kanarazu renraku shite ne.

  Be it by phone or email, make sure to contact me.

  にしろ〜にしろ is the softer conversational variant listing two options

• ・Register: にせよ is formal/written; にしろ is slightly more spoken but still stiff.
• ・The two items are usually a contrasting pair or opposites.
• ・The final clause states a judgment or conclusion that applies regardless of which case is true.

Commonly confused with

The JLPT rarely asks whether you recognise a pattern — it asks which of several similar patterns fits. These are the ones にせよ〜にせよ is tested against.

• に応えて — In Response To / Living Up To
• ～も～ば～も — Both This And That
• ～ことは～が — True, But…
• ～つつ — While / Even Though
• ～というと／といえば／といったら — Speaking Of
• にかかわらず — Regardless Of / Irrespective Of
• にもかかわらず — In Spite of It All
• ～のみならず — Not Only, But Also