New Delhi:Police cannot commence an independent investigation of the offences under the Pre-Conception and Pre-Natal Diagnostic Techniques (PCPNDT) Act, the Supreme Court said on Thursday. A bench of Justices Sanjay Karol and N Kotiswar Singh held that authorities designated under the law must take action in such cases. The PCPNDT Act was enacted with the intent to prohibit the use of prenatal diagnostic techniques for determination of the sex of the foetus.