Bulgaria's reformed Penal Code entered into force on Saturday, with hopes to bring the country's judiciary closer to EU standards.
The fresh act introduces the "observing prosecutor" who should be in charge of a case from the beginning of an investigation until charges are brought in court.
It is believed that in this way the responsibility of the prosecution will be set more clearly.
But the efficiency of the new legislation has been questioned by some statesmen, including the interior minister.
Rumen Petkov stood against the decision to set a two-year deadline for an investigation. The revelation of some organized crime acts can take more time, Petkov argued.
Bulgaria has been put under pressure from the European Union to reform it justice system. The bloc's experts say that the country is still inefficient in tackling crime and high-level corruption.
In the meantime, Sofia is aimed at entering the EU next January, and has little time left to complete the necessary reforms.