Rahul Gandhi was detained on Tuesday after he led a protest and sat on a road in the heart of the capital while his mother Sonia Gandhi was being questioned by the Enforcement Directorate.
The Congress leader, surrounded by scores of policemen, sat on Rajpath - the high security avenue near parliament and top government offices - as he protested over a range of issues from price rise and GST to the targeting of opposition leaders by probe agencies, reports NDTV.
After a stand-off that lasted for about 30 minutes, the Congress MP was detained by the policemen who lifted him and put him in the bus along with other MPs who had already been detained.
"India is a police state, (Prime Minister Narendra) Modi is a king," Rahul Gandhi said before his detention.
Mr Gandhi was virtually the last man standing as the police debated whether to detain him.
In another part of the city, his mother and Congress president Sonia Gandhi was at the Enforcement Directorate for the second round of questioning in connection with the National Herald case.
Sonia Gandhi was accompanied by her daughter Priyanka Gandhi Vadra to the probe agency's office. Rahul Gandhi also went there before joining the protest at parliament.
The Congress MPs were protesting over the opposition "being silenced" in parliament a day after four party MPs were suspended for the entire monsoon session. The MPs, who planned to march towards the Rashtrapati Bhavan, were stopped at the Vijay Chowk crossing.
"We're protesting as per the instruction of the police. All of this is a conspiracy by PM Modi and Amit Shah to completely destroy the opposition and muzzle our voices. We won't be scared, our fight will continue," said Congress leader Mallikarjun Kharge, the Leader of Opposition in Rajya Sabha.