The word "most juridical" implies a strong association with legal matters, courts and law. Therefore, antonyms would be words that are not related to that realm. Some options might include "unlegal," "unlawful," "extralegal," "informal," or "unofficial." Each of these terms suggests a deviation from formal legal process, and communicates an absence or disregard for the established rules of law. Other possible antonyms could include "amoral," "illegitimate," or "immoral," each of which implies an unethical or immoral aspect that contrasts with the uprightness suggested by "most juridical.