The government is implementing the unique ID project under the leadership of Nandan Nilekani and UIDAI has plans to issue the UID numbers this year. 

The UID authority has mentioned that the UID database will not be read by anybody and will be used only for authentication, but in the absence of any law (like the right to privacy) the concern for privacy remains. Also, there is no guarantee that the purpose of the UID system will not be altered in future. In the US the social security numbers were introduced with the sole purpose of distributing the retirement benefits but the purpose changed with time.

When all transactions will get linked to a single number the same may be used by the various security agencies of the state to keep a check on the activities of the citizens. This may diminish the freedom of the law-abiding citizens and may interfere in their privacy.

Though the UID chairman has said that UID numbers will be voluntarily, its requirement for various services in future and its mandatory character cannot be ruled out.  Nilekani has probably therefore called for a larger debate on privacy and privacy laws.

While the Supreme Court has upheld the right to privacy of citizens as part of the right to life and liberty, in the absence of any formal law it may be difficult to enforce and may lead to the misuse of the UID information by various agencies of the government or the private sector. 

Further, since the UID database will be accessed (even for authentication) by multiple agencies for multiple purposes, the probability of its misuse is higher.

The misuse of mobile numbers in the hands of private players despite registration in the Do Not Call Registry (DNCR) and limited legal recourse thereafter is evident to all.  The international experience shows that both the government and the private sector have failed in cases of leakage of data and identity theft.

Thus, the question is, will the UID project breach your privacy?