いかんにかかわらず / いかんによらず / いかんをとわず

These three expressions – いかんにかかわらず、いかんによらず、and いかんをとわず – all mean "regardless of", "irrespective of", or "no matter what". They are used to express that the outcome or decision is the same no matter what the preceding condition may be. These are highly formal expressions found in written language, official announcements, rules, regulations, and formal speeches.

Structure

These expressions attach to a noun (often with the particle の):

• Noun + の + いかんにかかわらず
• Noun + の + いかんによらず
• Noun + の + いかんをとわず

The word いかん (如何) means "how" or "in what way" and is itself a formal word. Combined with にかかわらず ("regardless of"), によらず ("not depending on"), or をとわず ("without asking/questioning"), these patterns all convey the same meaning with only subtle stylistic differences.

Nuance differences

While the three forms are largely interchangeable, there are slight tendencies:

• いかんにかかわらず is the most common of the three and sounds the most neutral in formal contexts.
• いかんによらず emphasizes that the decision/outcome does not depend on the condition.
• いかんをとわず emphasizes that the condition is not even questioned or considered.

Related forms

A closely related expression is いかんで / いかんによって, which has the opposite meaning – "depending on." Compare:

いかん can sometimes appear without の, attaching directly to the noun (e.g. 理由いかんにかかわらず), though the version with の is more common.