Washington (CNN) Attorney General William Barr on Tuesday criticized what he sees as a growing trend of courts issuing nationwide injunctions to pause policy moves within the Executive Branch, which threaten separation of powers and thwarts President Donald Trump's agenda.

"These days, clashes between Congress and the executive steal the headlines, as I know very well. But clashes between the judiciary and the political branches are also very weighty," Barr said at a speech to the American Law Institute in Washington, DC. "These nationwide injunctions have frustrated presidential policy for most of the President's term with no clear end in sight."

In his speech, Barr took aim at recent decisions by two federal appeals courts that blocked the Trump administration from rescinding the Obama-era Deferred Action for Childhood Arrivals program, which protects young undocumented immigrants who came to the United States as children from being deported, citing them as ways he sees courts disrupting the executive branch's ability to create and carry out policy.

In one case, the Ninth Circuit Court of Appeals upheld in November a nationwide injunction allowing DACA to remain in effect. The Department of Justice has a pending request with the Supreme Court to take up an appeal, but the justices have so far declined to do so, which Barr criticized in his speech Tuesday evening.

"But the court has not granted any of those requests, and they languish on the conference docket. Unless the court acts quickly and decisively, we are unlikely to see a decision before mid-2020 at the earliest -- that is, right before the next election. It is hard to imagine a clearer example of the stakes of nationwide injunctions."

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