About a thousand people took to the streets of Bucharest, the capital, to oppose the amendments, just months after mass protests rocked the country after the passage of an emergency measure relaxing penalties for official corruption.
Those protests in February, which at times drew more than half a million people and lasted for more than two weeks, were the largest the country had seen since the fall of communism more than two decades ago. The government rescinded the emergency decree and was forced to fend off a no-confidence motion brought about by the opposition.
The protests on Wednesday were far smaller, but organizers said they were prepared to urge people to return to the streets if necessary.
“This decision of the judiciary committee is very important,” said Cristian Pirvulescu, the dean of the political science department at the National School of Political Studies and Public Administration in Bucharest. Politicians, Mr. Pirvulescu said, “probably believed the civic movement was finished and they could restart disruptions against the rule of law.”
“In Bucharest we had a small but very determined protest, and the reaction was very rapid,” he added.
Prime Minister Sorin Grindeanu and Liviu Dragnea, the leader of the Social Democratic Party, both quickly spoke out against the measure, saying that they did not support pardons for those convicted of corruption offenses.
Mr. Dragnea, whose party is the country’s largest, is ineligible to be prime minister because he is serving a two-year suspended sentence for electoral fraud and is facing abuse-of-power charges.
The law barring those with convictions from serving as ministers was introduced in 2001 as Romania prepared to join the European Union. In January, a month after parliamentary elections, the country’s ombudsman questioned its constitutionality. Mr. Dragnea has said that the law is unfair. The Constitutional Court had already postponed its ruling four times before eventually dismissing the constitutional challenge on Thursday.
“I think this is a signal, but we don’t yet know the motivation of the court,” said Radu Delicote, a strategist at the political consulting group Smartlink Communications. “They haven’t issued any official statement yet.”
Mr. Delicote described Thursday as a good day for the rule of law and institutional checks and balances in Romania. But others were more cautious.
“I wouldn’t use big words to describe today,” said Laura Stefan, an anticorruption expert and a former director in the Romanian Justice Ministry.
“It is another day where we survive,” Ms. Stefan said. “What we see recently is that each day is a battle. These are not normal times. The ombudsman going to the Constitutional Court to ask if someone who has a criminal record can become prime minister, is that a normal question in a normal country?”