לזכות ידי"נ הרה"ג ר' מאיר זאב שטיינמץ וכל ב"ב לברכה עד בלי די!
The Abarbanel [הקדמה לספר שופטים] discusses at length the differences and similarities between Judges and Kings - שופטים and מלכים. Similarities: They are both appointed by Beis Din and the Jews accepted them upon themselves. They both waged wars and executed judgment. They would both punish as necessary without having to find a source in the Torah if the circumstances required it. We were obligated to both fear and honor both of them. If one doesn't listen to them he is חייב מיתה.
Differences: A שופט is not appointed with anointing and a Navi. A שופט is expected to judge primarily according to Torah law [as opposed to a king who judges based on the present reality and needs – as the Ran elaborates in דרוש י"א - that a king judges based on תיקון הקיבוץ המדיני ]. That is why they were called "שופטים" – they were expected to judge properly without reverting to supra-legal judgments. The only time they had to judge not according to halacha was when there was no king to do so. That is why we find at times that they were called "מלך " [Shoftim 15 with respect to Avimelech, Yiftach didn't go to Pinchas to release himself from his vow because "אני מלך"]. A שופט is not obligated in the mitzvos of a king such as not having to many wives or [lihavdil] horses etc. etc. See the Abarbanel for his words are illuminating!
But untershte shurah ["bottom line" in Old French] – what is the DEFINITION, the גדר, of a שופט
[עי' אבני נזר יו"ד שי"ב מאות מ"ז ואילך]?
So it would appear as follows [we base our words on the באר מרים from page 11]: We find another person who is part-king-part-not. A נשיא [not the one that YU is "historically investituring" in a few days time but the head of the Sanhedrin]. It says in Horiyos [11b] that Rebbi asked whether he should bring a שעיר when he sins [like a king] or a שעירה [like a regular person] and he was told that since he is not a complete נשיא [there was another one in בבל] he should bring a שעירה. If not for the נשיא in בבל however, Rebbi would bring a שעיר like a king. The Achronim ask how we can relate to him as a king when the law is that a king may not forgive his כבוד while a נשיא may? [עי' קרן אורה וחק נתן]
The nature of a נשיא can be explained based on the Rambam [Sanhedrin 26/1 and Sefer Hamitzvos ל"ת שט"ז] who writes that the infraction of cursing a נשיא refers both to the נשיא of the Sanhedrin and to the king. The Ramban quotes this and adds that both נשיא and מלך are leaders. The נשיא is the spiritual, Torah leader while the king is the political leader.
This means that if we have to wage a מלחמת מצוה, that is the domain of the נשיא for this is a מלחמת תורה. But if we wage a מלחמת רשות that is the domain of the מלך because it is a political matter [as the Rambam delineates in Hilchos Melachim]. A שופט is similar in that his job is to "judge" according to the strictures of the Torah – משפט התורה. But the special supra-legal laws that pertain to a king [פרשת המלך in Sefer Shmuel] apply only to him and not to a שופט since these laws are not part of the regular legal structure. A נשיא [and שופט] can likewise forgo his honor [מוחל על כבודו] because the law of אימתו מוטלת עליך – a king must be feared, doesn't apply to one who is not a full fledged political leader but merely a Torah based leader. But if one defies a נשיא receives the death penalty as the law is regarding a king [עי' סנהדרין ס"ו. ד"ה בנין אב] for he is a leader and one must listen to a leader. [This is an especially cogent argument according to the Chasam Sofer או"ח י"ח who says that the חיוב מיתה of מורד במלכות stems from the חרם we accepted upon ourselves – see Vayikra 27,29 and the Ramban. If so the קבלה was also regarding a נשיא, particularly according to the opinion that Yehoshua was a נשיא and about him the pasuk says explicitly that we must not defy his word – לא ימרה את פיך ].
We see this principal in Sanhedrin [5a] and Horiyos [11b]. On the pasuk לא יסור שבט מיהודה ומחקק מבין רגליו - the gemara derives that שבט [staff] refers to the Exilarchs [leaders of the exile] in Bavel who punish their people with a staff. ומחוקק מבין רגליו refers to the grandchildren of Hillel [הנשיא] who teach Torah - meaning the נשיאים as the gemara says. A focused reading of this gemara reveals that the head of the exiles were considered kings [עי' רמב"ם סנהדרין פ"ד הלכה י"ג ושו"ת הריב"ש רע"א] - a staff symbolizes personal rule. A נשיא is also a leader but as a מחוקק - legislator of Torah law.