Resolving the 'Probative Value' Puzzle

Kya hai yeh 'probative value' ka matlab? Main textbooks padhke confused hoon, kya yeh ek new concept hai ya existing mein rehte hain ek naam badalne se? Sabhi textbooks keh rahe hain ki yeh kya hai, lekin actual mein kaafi confusion lagti hai. Agar koi example de sakta hai jahaan iske application ke baare mein kuch detail se pata lagta, to shukriya ho. Judicial Services ke liye isse clear samjhne mein madad milegi.