Hello Kamal Prasoon Sinha,
I am not sure how did you arrive to the conclusion you mentioned:'.........is voidable in the court of law'.
Before going into the legality aspect, I hope everyone is clear the ACTUAL BASIS/REASON why some Companies get such a Document signed at all. Quite a few companies, especially US-based, HAVE THE GENUINE NEED to protect their trade secrets & IPRs. The need for this precaution is well-recognized the world over--pl note that this is different from HOW this is enforced.
Now, pl note that the Factuals of the Legal position on any such Agreement [this could be equally applied to Employment Agreements too....but that's beside the present issue] is this: Once an individual signs a document [in this case, the Bond/Agreement NOT to join a Competitor before a particular period of time], he/she is WILLFULLY BINDING himself/herself to that said position. Once he/she signs such a document, he/she can't later say it's not valid--if he/she knew it wasn't valid, then why did he/she sign it at all?
Hope you got the point.
The ONLY WAY the individual can get away EVEN AFTER SIGNING SUCH A DOCUMENT, will HAVE TO BE to show to the court[comfortably assuming that the Company WILL go legal in case of any violation] that the Company forced him/her into it by whatever means & ways. As you can see, that's a tough call to prove.
It's also IMPORTANT to remember that once the case goes legal AND the individual takes the above-mentioned stand, one can be REASONABLY SURE that the Company COULD PORTRAY that the individual acted contrary to the interests of the company by violating the IPR Act, etc., etc.....
And let's face it: EVEN IF there are Court Decisions/Rulings saying that such Agreements/Binds are illegal, just try to talk to any reasonably good lawyer. He/she will show you 'hazaar' ways to argue in the court that THOSE RULINGS DON'T APPLY TO THIS CASE.
Hope you get where this will be leading to--at the very minimum you will be stuck with a case rather than work in peace.
So, in a nutshell, pl sign such a document ONLY IF YOU INTEND TO HONOR IT. Else, look for another job where this won't be an issue.
Rgds,
TS