MANILA - Senator Antonio Trillanes IV on Wednesday claimed that presidential candidate Davao City Mayor Rodrigo Duterte has more than P200 million in deposits in undisclosed bank accounts.

While many were startled with the new allegations, not a few wondered how Trillanes got hold of the information when such are supposedly protected by the bank secrecy law.

[ READ: Trillanes: Duterte a 'fraud,' didn't declare P211M in SALN ]

University of the Philippines (UP) College of Law Professor Tranquil Salvador on Thursday explained nuances of the bank secrecy law on DZMM's "SRO."

According to Salvador, the law on secrecy of bank deposits prohibits financial institutions from disclosing any information concerning deposits.

But with the law in place, how can an individual get information about deposits?

"Maaring magtataka kayo, saan nila maaring makuha ito? Ibig pong sabihin nito ay may mga nag-disclose sa loob ng bangko or the banking institution po na tinutukoy na kung sa totoo pong nag-e-exist ito na meron po talagang account," Salvador explained.

Given the legal safeguards on the secrecy of bank deposits, Salvador pointed out that some resort to extra-legal ways to father information.

"Isa sa nga paraang ginagawa sa mga usaping ganito, practical, which I am not saying is legal, may iba dyan, kasi nga karamihan ng bangko natin ay universal banks, ibig pong sabihin n'yan, centralized 'yan. Kunyari ikaw Alvin, isa kang manager, type mo pangalan ni Ms. Bernadette, 'pag nakita nila 'yan, pwede silip agad 'yun eh," Salvador explained.

According to him, some bank personnel have access to information of depositors and they are vulnerable to be sources of illegal disclosures.

However, there are other ways to legally obtain information on bank deposits. One of these is to secure a court order for the disclosure.

"Ayon sa secrecy of bank deposits, iyan ang commitment nila sa lahat ng depositors, one of the few instances na pwede lang silang mag-disclose is if there is a court order na nire-require sila to disclose ang detalye ng isang particular account," Salvador explained.

Another legal way to bypass the law is through the execution of a bank secrecy waiver.

Duterte's rivals are challenging him to execute a bank secrecy waiver in order to finally put the allegations to rest.

[ READ: Roxas dares Duterte: Sign a 'real' waiver ]