Paul Karp Chief political correspondent

Migration and legal experts have warned the true number of visa decisions affected by invalid refusals of ministerial intervention is likely to be in the tens of thousands, after the high court rejected bureaucrats’ ability to block applications.

Advocates fear the court’s decision on Tuesday rejecting a Coalition-era policy that cases must show “unique or exceptional circumstances” could result in a hasty legislative fix.

Instead, they are urging the government to consider granting visas to desperate applicants including women fleeing domestic violence, asylum seekers who arrived by boat and exploited workers.

A majority of judges of the high court found that home affairs department decisions in line with the 2016 instruction not to send cases to the minister unless they met subjective criteria were not consistent with the Migration Act, which gives the power to intervene to the minister “personally”.

Abul Rizvi, former deputy secretary of the immigration department, said it was an “extraordinary decision”.

Department of home affairs documents suggest in the relevant period after 2016, it routinely received in excess of 1,000 applications a year for ministerial intervention under section 351.

Rizvi said given the act contains several powers of personal intervention it was “a certainty” the number of applicants affected since 2016 would run into the tens of thousands.

Rizvi said although the “god-like powers” in the act mean the minister cannot be compelled to make a decision, the court had ruled it “still has to be the minister’s decision not to consider” an application.

“You can’t have a request for ministerial intervention not going to them at all, they have to touch the minister at some point,” he said.

“[Former immigration minister] Peter Dutton designed a system that meant the vast majority never went near him.

“[Current minister] Andrew Giles would never do any other work in his life if had to deal with them all.”

Sanmati Verma, managing lawyer at the Human Rights Law Centre, agreed that tens of thousands of decisions were probably affected, given the many applicants “who are forced to supplicate before the minister for a better outcome than they received at the tribunal”.

Verma said the decision may also affect “people who arrive by boat and are at the mercy of the minister’s powers” before they can apply for a bridging visa, including 12,000 people who were refused protection visas through the fast-track process.

“The decision has far-reaching consequences for these people and the administration of the minister’s personal powers across the board,” she said.

Verma noted that justice James Edelman had observed the act could be amended to permit departmental officials “to exercise a liberty to decide whether to refer to the minister an application for the exercise of the personal override power”.

The decision shows “the need for a serious reckoning about the minister’s powers under the act”, she said.

Stephanie Lee, a senior solicitor at the Immigration Advice and Rights Centre, said a legislative fix is most likely but her community legal centre “hopes that the outcome of this case results in the minister looking into more of these cases”.

“They’re people at the end of the road, who’ve exhausted every other avenue … in very desperate situations,” she said.

Lee cited women fleeing domestic violence whose partners promised but then failed to apply for partner visas, leaving them with “Australian citizen children and no other visa options in Australia”. “We see this form of immigration-related abuse occur frequently,” she said.

Another category of applicants is exploited workers, who due to the exploitation no longer meet the criteria for nomination for permanent residency, resulting in their presence in Australia unlawful.

“We’re very excited by this case,” Lee said. “We hope for more oversight by the minister considering these situations more closely.”

On Thursday Giles said the decision was “very substantial” and the government is “carefully considering [it] and taking advice”.

Asked if thousands could be affected, Giles repeated that taking advice was “the only responsible course of action”.