You don't get it. Torah is a guideline that teaches you how to walk in His ways. There was only one person who could keep the Torah perfectly without mistakes, and that's Yeshua. The Torah provides proper consequences, steps to correct and repent from the sin committed. 
You need to really study Torah out a bit before you throw around fluff statements that you don't know anything about.
Sin is when you transgress the Torah- whether it's before or after salvation. When you sin (not IF you sin), His Word teaches you and shows you what steps you must take to repent and restore with your brother.
Catching someone sinning isn't enough to throw away the Torah of G-d. For it's the human being that has messed up. It's the human that has failed TOrah. The Torah itself is perfect! G-d's word is perfect!
		
		
	 
Is sin only the violation of 
the law? How?
 
 
13For 
until the law 
sin was in the world: but sin is not imputed when there is no law. Rom 5
 
16The law and the prophets
 were until John: since that time the kingdom of God is preached, and every man presseth into it. LK 16:16 
 
4Whosoever committeth sin transgresseth 
also the law: for sin is the transgression of the law. I John 3
 
For comparison please read sin is also lack of faith - 
 
23And he that doubteth is damned if he eat, because he eateth not of faith: for whatsoever is
 not of faith is sin. Rom 14
 
Not only do we have the promise of God given through Jeremiah we also have - 
 
19Wherefore then serveth the law? It 
was added because of transgressions, 
till the seed should come to whom the promise was made; and it was ordained by angels in the hand of a mediator. Gal 3
 
We are delivered from 
the law - 
 
6But now 
we are delivered from the law, that being dead wherein we were held; that we should serve in newness of spirit, and not in the oldness of the letter. Rom 7
 
And we are told to throw the law out - 
 
30Nevertheless what saith the scripture? 
Cast out the bondwoman and her son: for the son of the bondwoman 
shall not be heir with the son of the freewoman.
 
We have a choice - 
 
4Christ is become of no effect unto you, whosoever of you are justified by the law; ye are fallen from grace. Gal 5