WASHINGTON — The Justice Department has refused to disclose key documents from the Trump administration’s planning of the “zero tolerance” policy that separated thousands of migrant families at the U.S. border, according to a document filed in a class action lawsuit in Arizona late Friday.

Among those documents not given to plaintiffs lawyers representing separated families seeking damages was the agenda from a May 3, 2018 meeting, which NBC News has reported included a show of hands vote to move forward with separating families.

In requesting documents from the Trump administration’s planning for zero tolerance, the lawyers representing the separated families argued the materials could show the officials intentionally sought to inflict emotional harm on the children and parents they separated. Lawyers for the Biden Justice Department were given till April 2 to respond, and then asked for an extension until Friday, April 9.

The materials requested include emails between top Trump administration officials and minutes of high-level meetings during the planning of the policy, according to court documents. The Trump administration had invoked executive privilege to keep the materials private and denied the materials to lawyers as part of discovery in the lawsuit.

The Biden administration did agree to hand over some documents, largely by unredacting previously redacted material. But Justice Department lawyers argued in the filing that the government must protect the right of the government to keep certain planning documents confidential.

“Those privileges protect institutional interest in the decision making process and the ability of a wide range of government employees to provide candid advice,” Justice Department lawyers said in their reasoning. “At the same time, the United States recognizes the significance of this matter and has substantially narrowed its privilege claims here.”

The government lawyers went on to say that not all of the documents it was asked to provide are relevant to the case, some being generally related to immigration but not zero tolerance.

The plaintiffs’ lawyers disagreed. In a response, they said: “the documents sought relate to the government’s awareness and intent in directing the separation of families and the resulting harm to families, which are highly relevant to the plaintiffs’ claims and the government’s asserted defenses.”

The Biden administration has condemned the separation of migrant families by the Trump administration and has formed a task force to reunite those who remain separated. As a candidate, Biden called the Trump administration’s policy “criminal” and said he would leave it to his Justice Department to decide if there should be a criminal investigation.

Last week, a senior Department of Homeland Security official said “accountability” for family separations fell under the jurisdiction of the Justice Department, and “is not part of what the task force was tasked to do.”