The first article of the Constitution says "ALL legislative powers...shall be vested in a Congress."  The second article vests "the executive power...in a President."  The third article places the "judicial power of the United States in one Supreme Court" and "in such inferior Courts as the Congress...may establish." 

Separation of powers serves several goals.  Separation  prevents concentration of power (seen as the root of tyranny) and provides each branch with weapons to fight off encroachment by the other two branches.  As James Madison argued in the Federalist Papers (No. 51), "Ambition must be made to counteract ambition."  Clearly, our system of separated powers is not designed to maximize efficiency; it is designed to maximize freedom.

Judge Cannon, a Trump appointed Federal judge, clearly demonstrated political bias in the handling of the Trump Mar-a-Lago case she is currently the presiding judge over. At the very least she should have recused herself from the case.

Judge Cannon took the unusual step of temporarily blocking the DOJ’s ability to use the 100 classified documents to investigate those crimes. Now the DOJ has appealed that ruling to the Eleventh Circuit Court of Appeals, and little wonder as to why: The very first sentence of its appeal says that the lower court blocked “the Executive Branch’s use of its own highly classified records in a criminal investigation with direct implications for national security.”

While Trump has argued he declassified all classified documents, which is not necessarily a defense to the Espionage Act, and certainly not a defense to taking government records, his attorneys have not made that argument. Nor did Cannon ask for evidence of declassification. The payload of documents the FBI recovered from Mar-a-Lago does not alone prove that Trump is guilty of crimes, but it certainly shows that the independent federal judge who found sufficient evidence to sign the search warrant was right to do so. Trump is a person of interest because he admits he took these government documents, including classified documents, upon leaving office. Frankly, if it didn’t involve national security he should, nonetheless, be treated like any private citizen: fairly, not specially. Cannon says, “Plaintiff has claimed injury from the threat of future prosecution and the serious, often indelible stigma associated therewith.” Well, yes, Trump may be harmed—because there is probable cause to believe crimes have been committed and the FBI may have evidence of it.

As DOJ points out in its filing, classified information must be “owned by, produced by or for, or [be] under the control of the United States government.” One of the authors, Eisen, helped write Executive Order 13526, the order issued by President Barack Obama which articulates that principle and which the government cites in its motion to Judge Cannon for a partial stay. The special status of classified documents is also rooted in the case law, including the seminal precedent in this area, Nixon v. GSA. It held that only the current president can assert executive privilege relating to “state secrets and sensitive information concerning military or diplomatic matters.” Many additional laws and rules apply to the handling of such materials, including that they be stored in or utilized in special, secure government locations. A former president’s heavily trafficked resort is certainly not one of them.

A specialist in separation of powers, Peter M. Shane, who is a legal scholar in residence at N.Y.U., said there was no basis for Judge Cannon to expand a special master’s authority to screen materials that were also potentially subject to executive privilege. That tool is normally thought of as protecting internal executive branch deliberations from disclosure to outsiders like Congress.

In Summary: 

Error #1: The court has no jurisdiction over this matter.
Error #2: A district court has no authority to block a criminal investigation. 
Error #3: The ruling is simply incoherent with respect to executive privilege.
Error #4: Normal people don’t get special masters when the FBI executes search warrants against them.