What sort of throws are illegal in Muay Thai and why?

Question

I started to watch Muay Thai recently, and something I can't really wrap my head around is exactly what throws are illegal. Muay Thai abstains from many throws and takedowns you'd find in grappling sports, but it still has leg sweeps and throws from the clinch. I know that Muay Thai does not allow groundfighting, but I never even see a shoulder or hip throw. Rules aside, those seem like good options in a clinch and can put an opponent on the ground as you remain standing, just like leg sweeps.

So what's the rule-of-thumb for a legal throw in Muay Thai and what's the motivation for it? I have considered if throws were just historically unused, but apparently the martial arts (Muay Boran) that formed the basis of Muay Thai had grappling and groundfighting. I have also wondered if it has to do with a history of safety regulations, but I only found information about fighting equipment, weight classes, banning groin strikes, the usual stuff.

Answer 1

I think Sylvie conveys the right feeling in this article:

I’ve fought over 100 times in Thailand and honestly I have never had a completely clear picture of what is and is not a legal throw in Muay Thai. There are some very obvious fouls, but others seem a gray area. I’ve had a vague sense that you cannot lift an opponent, or that you can’t “back break”, or use the calf or “hooking” with feet to trip, but it seemed that some of the more effective throws that [other fighters] do in training were often in the gray area.

She ends the article with a supposedly complete, rulebook-based list of illegal moves, but it's important to keep in mind how little the sport approaches it in that lawyerly way. This is to be expected in any sport where you're allowed to clinch for a prolonged period of time, and where you can kick the legs and knock your opponent to the ground, but you aren't supposed to wrestle for takedowns or focus on big throws. That combination of factors creates a fundamentally fuzzy border between good technique and fouls.

(This is true in the other direction, too: the instructions for a driving kouchigari trip in one of the best judo tomes reads "you must strike him with your elbow slightly inward of his diaphragm." Strikes are forbidden, but it would be ludicrous to try to codify the difference between a strike-to-do-damage and the necessary strike involved in knocking someone down.)