A specially-designated tribunal on Tuesday lifted the ban on the Students Islamic Movement of India.
In a 267-page judgment, Justice Geeta Mittal, a Delhi High Court judge, stated that the material provided by the Home Ministry to justify the ban, was insufficient.
The tribunal had found no evidence against the outfit, SIMI's lawyer Trideep Pais told rediff.com.
He added that the verdict was a slap for the legislators, as they had not applied their minds before banning the outfit.
"When the ban was initially slapped on SIMI, the Prevention of Terrorism Act was in existence. This means that the outfit is still facing terrorism charges. However, if there is no evidence against SIMI under the Unlawful Activities (Prevention) Act, then the charges of terrorism are meaningless," said Pais.
Speaking on the implications of the judgment, Pais said, "There are several immediate implications. A lot of people across India are being prosecuted for being members of the organisation. They have been prosecuted solely for their membership. All these prosecutions will suffer. SIMI is not an underground organisation, it is an over ground organisation like the Lions club or the Rotary club".
The government maintains that SIMI still indulges in communal activities and it is a threat to the country.
The organisation has been banned by the Centre for the last seven years and the government issued a fresh notification in February this year to extend the ban for another two years under Unlawful Activities (Prevention) Acts.
State governments across the country had filed their affidavits, supporting the ban, to the tribunal. Pais said that although the matter had been heard in several states, the verdict given by the Tribunal on Tuesday meant that the ban on SIMI had been lifted nationwide.
He added that he had not read the 267-page judgment completely and would be able to comment further after reading the document.
Pais refused to comment on the SIMI's future course of action.
The Centre would appeal against the judgment in Supreme Court, according to Home Ministry sources.