Some 1,500 students are facing prosecution over the massive protests that rocked the country for four months, including 160 who are still in prison, the International Commission of Jurists (ICJ) said in a report.
At least 42 people were killed when opponents of President Nicolas Maduro took to the streets in February to protest rampant crime, runaway inflation and shortages of basic goods in the country with the world's largest proven oil reserves.
Judges and prosecutors, under heavy political pressure, have made little progress in investigating the deaths or allegations of the torture of demonstrators, the ICJ said.
And they have turned a blind eye to surging crime rates in Venezuela — including some 15,000 murders in the last year alone, the ICJ said, pointing out that instead the judiciary had cracked down on dissidents.
"A robustly independent judiciary, prosecutorial service, and legal profession are needed now more than ever to protect people's rights in a democratic state," said the ICJ's Secretary General Wilder Tayler.
"Without them, respect for the rule of law and for human rights quickly goes into a downward spiral," he added in a statement.
A judge in Caracas ruled on Thursday that opposition leader Leopoldo Lopez would have to stand trial on charges of instigating violence at an anti-government demonstration in February.
The 43-year-old, Harvard-educated economist who leads the opposition Popular Will party, is being held at a military jail on the outskirts of Caracas as a self-proclaimed "political prisoner" and "prisoner of conscience".
"This is only one example of how the judiciary as a whole is being used against politicians and dissidents," ICJ commissioner Carlos Ayala told reporters in Geneva.
The case is "an example of how dangerous it is for democracy and the rule of law (to use) the judiciary to persecute political dissidents," he said.
Maduro has likened the protests to a coup designed to oust him ever since he succeeded late firebrand leader Hugo Chavez, blaming the United States for masterminding them.
Washington has dismissed the allegations.
The lack of independence in the judiciary helped spark the demonstrations and is contributing to the harsh treatment of the protesters, the ICJ said.
Venezuela's judiciary "is seriously threatened," and this is undermining democracy and rule of law in the country, said the report.