Is Trump the "chief law-enforcement officer of the United States"?

Question

This article from Business Insider, and many others, say that

President Donald Trump falsely designated himself the "chief law-enforcement officer of the United States" while speaking with reporters on Tuesday.

Is that the case?

Answer 1

No he is not.

The White House web-page on the Executive Branch explains:

The Attorney General is the head of the DOJ and chief law enforcement officer of the federal government.

According to 28 U.S. Code § 503:

The Attorney General is the head of the Department of Justice.

Note: The actual claim isn't as strong as the question claims. Trump showed he wasn't sure by prefixing it with "I’m actually, I guess". His guess, in this case, was wrong.

Answer 2

In common usage of the term, yes, the President is the chief law enforcement officer of the nation.

Neither the constitution, nor the Judiciary Act of 1789 designate an official position called "Chief Law Enforcement Officer". The term "chief law enforcement officer", however, is one of common usage that has been applied to the U.S. Attorney General, and for the President of the United States as well. In fact, there are many chief law enforcement officers (Sheriffs for example), each holding an office with the duty and authority to enforce the law within a defined context.

Although the Attorney General is often referenced as the chief federal law enforcement officer, it is important to note that he is subordinate to the President, and serves at the President's pleasure. The position was created by the Judiciary Act of 1789 as follows:

And there shall also be appointed a meet person, learned in the law, to act as attorney-general for the United States, ...; whose duty it shall be to prosecute and conduct all suits in the Supreme Court in which the United States shall be concerned, and to give his advice and opinion upon questions of law when required by the President of the United States...

During the forming of the Constitution, there was debate over whether the Executive Branch of government would be plural, or have single head. Hamilton wrote forcefully for a single head executive in Federalist Paper #70, and ultimately, that is what exactly, and intentionally was put into effect by the Constitution. The President, a single person, was given the ultimate authority of the entire Executive Branch. It was the President, specifically, granted the authority, as Commander in Chief of the Army and Navy of the United States, as well as the state militias, and the duty to "take Care that the laws be faithfully executed". For an in-depth coverage of this topic see The Essential Meaning of Executive Power.

Although the Attorney General is the chief law enforcement officer within the bounds of his jurisdiction, it is important to consider that there are enforcement powers, such as calling up the militia, that are outside the authority of the Attorney General, and reside with the President alone. The Militia Act of 1792 gave the President the authority to call up the militia "whenever the laws of the United States shall be opposed or the execution thereof obstructed, in any state, by combinations too powerful to be suppressed by the ordinary course of judicial proceedings, or by the powers vested in the marshals by this act."

This was put to use in 1794 during the Whiskey Rebellion. President Washington activated the militia from neighboring states, and led them to the area of the revolt (or at least was with them, depending on the source), and personally met with the rebel leaders, which diffused the situation.

As the chief individual holding the office as the head of a branch of government that among its significant duties is the enforcement of federal law, it does not seem unreasonable to describe that individual, i.e. the President, as the chief law enforcement officer.

Trump is not simply "self-designating" the president as "chief law enforcement officer" of the nation. The term has been applied to the presidency in textbooks, books about the presidency, congressional records, articles about other presidents, and by other presidents themselves, all occurring prior to Trump's term as president.

For example, the following two quotes are from the book "Powers of the Presidency" by Congressional Quarterly, Inc. published in 2013 (partially available on books.google.com):

The Constitution instructed the president to "take Care that the Laws be faithfully executed" and to preside as chief executive over what would become a vast law enforcement apparatus. The president could invoke the authority of "commander in chief" and deploy the armed forces, including units of state militia, to enforce the law. And, because mercy may be a more effective means of promoting domestic tranquility than the sword, the president would be given extensive clemency authority - the power to grand pardons and reprieves. In other words, the president was to be the chief law enforcement officer of the United States.

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John Kennedy exercised the legal power of the president when, in September 1962, he deployed first U.S. marshals (and various other federal civilian law enforcement officers) and then regular army troops to Oxford, Mississippi. Kennedy was acting as chief law enforcement officer of the United States. He was, as Article II, Section 3, of the U.S. Constitution requires, "tak[ing] Care that the Laws be faithfully executed."

The term has been applied to other presidents (ourdocuments.gov)

Finally, Congressman Brooks Hays and Little Rock Mayor Woodrow Mann asked the Federal Government for help, first in the form of U.S. marshals. President Dwight D. Eisenhower, as the chief law enforcement officer of the United States, was presented with a difficult problem. He was required to uphold the Constitution and the laws, but he also wanted to avoid a bloody confrontation in Arkansas.

To get another president's view (or, at least his lawyer's view), there is Question #1 from 81 questions Congress submitted to President William Clinton in 1998. Here is the question, and Clinton's answer:

1. Do you admit or deny that you are the chief law enforcement officer of the United States of America?

CLINTON: The President is frequently referred to as the chief law enforcement officer, although nothing in the Constitution specifically designates the president as such. Article II Section 1 of the United States Constitution states that "the executive power shall be vested in a president of the United States of America," and the law enforcement function is a component of the executive power.

President Carter was more straightforward in remarks at a reception for police chiefs in 1980:

...And here in the White House, as president, of course, I have to be primarily concerned about our nation's security, about defense, about the maintenance of peace. But that responsibility cannot be separated from my own as the chief law enforcement officer of our country...

Some other references:

Judicial Watch referring to presidential candidate George W. Bush as possible future chief law enforcement officer

Baltimore Sun editorial referencing President Obama as chief law enforcement officer

2013 CBS article quotes constitutional law professor Jeffery Kahn referencing president as chief law enforcement officer

2005 NBC News Hardball Chris Mathews refers to president as chief law enforcement official of this country

Congressional Record Senator Sessions refers to President Obama as chief law enforcement officer