The Trump administration asked a federal judge on Friday to uphold the constitutionality of the controversial state immigration crackdown passed by the Republican-dominated Texas legislature.

The U.S. government isnt a party in the lawsuit challenging Texas Senate Bill 4, which bans so-called sanctuary policies that limit local police from cooperating with federal immigration authorities. But the Texas law has become a prominent test of whether courts will approve strong-arm tactics endorsed by President Donald Trump to pressure local jurisdictions into complying with federal deportation efforts.

President Trump has made a commitment to keep America safe and to ensure cooperation with federal immigration laws, Attorney General Jeff Sessions said in a statement Friday. The Department of Justice fully supports Texass effort and is participating in this lawsuit because of the strong federal interest in facilitating the state and local cooperation that is critical in enforcing our nations immigration laws.

SB 4 bars local jurisdictions in Texas from denying requests from Immigration and Customs Enforcement to hold suspected undocumented immigrants on the federal governments behalf. Adopting a policy of refusing such requests, known as detainers, can land public officials in jail for up to a year under the new law. SB 4 also allows local police officers to ask the immigration status of anyone they stop, drawing comparisons to an Arizona law derided by critics as the show me your papers law.

Several jurisdictions including Austin, San Antonio and El Paso filed lawsuits to overturn SB 4 shortly after Gov. Greg Abbott signed it into law last month.

The legal challenges accuse Republican lawmakers of trampling multiple constitutional principles.

Several federal judges have ruled in recent years that holding someone on an ICE detainer in a local jail if they would otherwise be allowed to go free violates the Fourth Amendments guarantees against illegal search and seizure. And because the federal government alone is charged with crafting immigration policy, the state of Texas cant create its own, or dole out criminal penalties for refusing to follow a state policy, critics argue.

The flurry of lawsuits were consolidated into a single case that will have its first hearing on Monday, when U.S. District Judge Orlando Garcia will consider whether to block the law from taking effect on Sept. 1 while the legal challenges move forward.

The Justice Department will try to convince the judge to give the law a chance.

Cooperation with federal officials is plainly permitted under the [Immigration and Nationality Act] and the Constitution, the statement of interest filed by DOJ reads. Parties may disagree with the state legislatures policy determinations in enacting SB 4, but nothing in federal immigration law precludes a state from directing law enforcement officers in the state to cooperate with the federal government, rather than merely permitting them to do so on an ad hoc basis.

The filing hinges on the argument that ICE detainers have changed in the months since Trump took office. The Department of Homeland Security started issuing administrative arrest warrants in April, along with detainer requests, in an apparent effort to make ICE holds less vulnerable to legal challenges.

That argument may not convince Garcia. He ruled earlier this month that the Bexar County Sheriffs Office in Texas violated the Fourth Amendment by refusing to release an undocumented immigrant for more than two months on the basis of an ICE detainer. The ruling appeared to strike a major blow against SB 4, which aims to force local jurisdictions to honor all such requests from ICE.

The Justice Departments filing took note of that ruling, but countered that the case began last year, before Trump took office. The Trump administrations new policy of including administrative warrants with ICE detainers solves the problem and is fully consistent with the Fourth Amendment, the filing says.

But avoiding the constitutional pitfalls presented by ICE detainers requires a warrant in a criminal case, not an administrative warrant for a violation of civil immigration law, according to Nina Perales, an attorney with the Mexican American Legal Defense and Educational Fund.

The Fourth Amendment in this context requires probable cause that the individual has committed a crime in order to deprive that person of liberty, Perales, one of several lawyers representing SB 4s opponents, told HuffPost. DOJ cannot hang its hat on the new detainer form when it comes to the stringent requirements of the Fourth Amendment.

Read the Justice Departments statement of interest below.