In the US targeting the knee is illegal under IKF. I am not sure about thailand, I would imagine its the same, but cannot find any information on it. I can probably find out if I really want to. If its not listed I suppose its legal. Theres been some debate about groin strikes as well, people saying they are legal in thailand. I just find it hard to believe that people will do a gentlemans rule of no elbows, but got no problem kicking eachother in the knee or nuts. as the supposed gentlemans rule of no elbows is because since guys fight for a living and frequently, they dont want to injure each other, so they can fight next week or what not. People tend to readily accept this idea, myself included, however that thought process totally contradicts kicking someones knee and ending their career. like hey dude dont elbow me and cut me, just shatter my knee instead. I have been told on here that thais will teep the knee. I cant say I have really seen any thais specifically targeting the knee, as the teep to the thigh is the target area when people are going to teep the leg. Im sure people have missed the thigh and hit the knee, by mistake or intentionally. Im sure video evidence can support a teep to the knee but most likely a "one off". I have yet to see anyone in MT specifically target the knee multiple times in a fight.