Campaigns were launched and demonstrations held here while MPs from several parties called for the changes to be reviewed. The parliamentary Joint Committee on Human Rights, among other bodies, criticised the changes.
During the Friday oral hearing on a judicial review application filed by HSMP Forum, a campaign group, Justice Sullivan said there was evidence of a breach of legitimate expectation and human rights legislation, and allowed the application.
The full hearing is expected to take place in two months.
In making the decision, the judge took into account the report of the Joint Committee on Human Rights and a large number of successful appeals by HSMP holders at the Asylum and Immigration Tribunal.
HSMP campaign sources told IANS that the High Court had previously rejected the paper application for "permission" but this was now overturned in the oral hearing.