相あい手て方がた当とう事じ者しゃ

• 相あい手て

  General term for 'partner', 'opponent', or 'the other person'; 相手方当事者 is a formal legal compound specifically meaning the opposing party in a dispute or proceeding.

• 当とう事じ者しゃ

  Means 'party concerned' or 'person directly involved'; 相手方当事者 narrows this to the opposing party in a legal context.

Compound of 相手方 (あいてがた, 'the other side') and 当事者 (とうじしゃ, 'party concerned'). A formal legal term.