Mr Chavez says the law will protect Venezuela from "imperialist" attacks
A new intelligence law brought in by Venezuela's President Hugo Chavez has caused concern among rights groups who say it threatens civil liberties.
Mr Chavez argues the law will help Venezuela guarantee its national security and prevent assassination plots and military rebellions.
The new law requires Venezuelans to cooperate with intelligence agencies and secret police if requested.
Refusal can result in up to four years in prison.
The law allows security forces to gather evidence through surveillance methods such as wiretapping without obtaining a court order, and authorities can withhold evidence from defence lawyers if it is considered to be in the interest of national security.
One part of the law, which explicitly requires judges and prosecutors to cooperate with the intelligence services, has caused concern among legal experts.
"Here you have the president legislating by decree that the country's judges must serve as spies for the government," Jose Miguel Vivanco, Americas Director for Human Rights Watch, said.
"The president is constantly calling opposition leaders coup-plotters and pro-imperialists, and that makes me suspect this law may be used as a weapon to silence and intimidate the opposition," said Alberto Arteaga Sanchez, a specialist in constitutional law.
"Among other problems with this law, any suspect's right to defence can be violated, and that's unacceptable," Carlos Correa, a leader of the Venezuelan human rights group Provea, said.
Mr Correa compared the law to the Patriot Act in the United States, which gave US law enforcement agencies greater powers to intercept communications and investigate suspected terrorists on American soil in the wake of the attacks on 11 September 2001.
Mr Chavez - who called the US Patriot Act a "dictatorial law" - denied the Venezuelan law would threaten freedoms, saying it falls into "a framework of great respect for human rights".
Mr Chavez used his decree powers to overhaul Venezuela's intelligence agencies, replacing the Disip secret police and the DIM military intelligence agency with the General Intelligence Office and General Counterintelligence Office, both under his control.
Interior Minister Ramon Rodriguez Chacin said the revamp was needed to combat "interference from the United States".
In December, Venezuelans rejected a package of constitutional changes aimed at cementing socialism into Venezuelan law which would have given the president the chance to stand for re-election as many times as he wished.