Legalism – Definitions
Legalists – a) declare what one must do to obtain God’s favor; b) declare what one must do to retain God’s favor; c) insist that Biblical rules are so important that new (man-made) ones need to be created around the Biblical ones, e.g. Talmud, man-made hedge of protection; d) focus on obedience to the Law (rules) to such an extreme that other ideas shrivel up, dwell on the law of God until they forget the love of God, what they preach may be true, but the whole is oppressive.
Doriani, Daniel M. Putting the Truth to Work: The Theory and Practice of Biblical Application. P&R Publishing, 2001.