O'Sullivan & Hilliard's The Law of Contract (2018 8 ed). p. 81.
4.24. While Walford was perhaps not the best case in which to suggest that a duty to negotiate in good faith was sufficiently certain, because there were few criteria in the agreement or otherwise to help the court to define what such a duty would mean in practice, Lord Ackner’s remarks go too far in suggesting that an obligation to negotiate in good faith should never be upheld: [...]
What'd differ if in which were removed? What's the significance of in which? What are some formal terms describing this issue?