Washington (CNN) The Trump administration is implementing a new asylum policy at the border that will result in potentially thousands of asylum seekers being turned away before they can plead their case in court.

The guidance, reviewed by CNN, also applies to refugee applicants -- immigrants seeking similar protections in the US who are still abroad.

Under new guidance given Wednesday to the officers who interview asylum seekers at the US' borders and evaluate refugee applications, claims based on fear of gang and domestic violence will be immediately rejected. In addition, the guidance tells officers they should consider whether an immigrant crossed the border illegally and weigh that against their claim, potentially rejecting even legitimate fears of persecution if the immigrant crossed illegally.

The change shows that even as the administration reunites families it separated at the border under a now-reversed "zero-tolerance" policy, it continues to pursue aggressive measures that could dramatically reshape US immigration law.

The move is likely to draw swift condemnation from immigration advocates and legal challenges. Advocates say international law is clear that asylum claims are valid even when a migrant enters a country illegally. They also argue that rejecting these traumatized immigrants puts their lives at risk immediately upon their return home.

The changes being implemented by the Department of Homeland Security come on the heels of Attorney General Jeff Sessions' decision last month that gang and domestic violence victims no longer qualify for asylum. Asylum protects migrants already in the US who fear persecution in their home country.

Sessions used his unique authority as attorney general last month to overturn an immigration appellate court's decision to the contrary, reversing course after years of allowing such victims to stay. His decision is now binding for all the immigration judges in the country.

But Sessions went further in his decision , suggesting in footnotes to his opinion that the rejection of such claims should come even before immigrants get before a judge and begin their court proceedings.

The new guidance from US Citizenship and Immigration Services fully implements those suggestions, instructing the officers who conduct the initial interviews at the border to reject asylum claims based on those fears. Beyond that, the officers are told to evaluate whether an illegal border crossing should also be grounds for rejection, as Sessions had also argued.

The guidance also places the burden on the newly arrived immigrant to articulate their asylum claim to the fullest extent of the complex legal standard during their initial interview.

"Claims based on ... the members' vulnerability to harm of domestic violence or gang violence committed by non-government actors will not establish the basis for asylum, refugee status, or a credible or reasonable fear of persecution," the guidance states.

Further, the guidance says officers "may find an applicant's illegal entry, including any intentional evasion of US authorities, and including any conviction for illegal entry where the alien does not demonstrate good cause for the illegal entry, to weigh against a favorable exercise of discretion" for asylum.

The guidance does note some illegal crossings may be warranted, including to "escape imminent harm," but adds that officers "should consider whether the applicant demonstrated ulterior motives for the illegal entry that are inconsistent with a valid asylum claim that the applicant wished to present."

When Sessions announced the decision, he said it "restores sound principles of asylum and long standing principles of immigration law" and is "a correct interpretation of the law" in his judgment. "Asylum was never meant to alleviate all problems, even all serious problems, that people face every day all over the world," he said.

Key to the issue is what's known as the credible fear interview. an initial screening as to whether an immigrant can pursue their claim before a judge. The interview threshold had been designed to consider that many of the immigrants may speak little English, have little to no legal understanding or education, may fear governmental authorities based on their home countries and may be traumatized from their journey. Roughly 80% of asylum seekers pass that screening, though a smaller share of them eventually achieve asylum. Administration officials have pointed to that gap as evidence of "abuse" of the system and a driving cause of a court backlog that makes immigration cases takes years to complete.

Most immigrants at the border today are Central Americans, coming from countries that are hotbeds of gang violence. Last month, more than 40,000 immigrants either tried to cross the border illegally or get through a legal crossing without paperwork, many of whom may have been seeking asylum.

Under the new guidance, thousands of them could be rejected by interviewers. Though legally the immigrants can appeal to an immigration judge, it's unlikely that without legal counsel they'd know that or how to pursue that option, attorneys fear. According to a USCIS official, immigrants who fail their interview are verbally explained they have the option to see a judge within seven days. But the immigration judges they would face are also bound by Sessions' order.

"Our laws do not offer protection against instances of violence based on personal, private conflict that is not on account of a protected ground, but over the years grounds for qualifying for asylum have greatly expanded far beyond what Congress originally intended," said USCIS spokesman Michael Bars. "USCIS is committed to adjudicating all petitions fairly, efficiently, and effectively on a case-by-case basis to determine if they meet all standards required under the law."

Advocates, however, argue that Sessions and the administration are searching for ways to effectively undercut asylum. The move is "disgraceful," said Archi Pyati, the chief of policy and programs for the Tahirih Justice Center, which protects and advocates for immigrant women and girls fleeing violence.

"The Asylum Division is now complicit in the disgraceful rejection of claims by women who cannot protect their lives if they stay in their home countries," Pyati said.