If Donald Trump, the presumptive Republican nominee for president, wins the general election in November, he would still be allowed to oversee operations and collect income from the more than 500 businesses he's listed in a personal financial disclosure form filed with the Federal Election Commission.

Some of these operations appear to be substantial (such as 401 North Wabash Venture, which Trump used to develop a hotel and condominium project in Chicago; Trump National Doral, one of his Florida golf courses; and a handful of entities related to the skyscraper he owns at 40 Wall Street in New York). Some go back to Trump’s earliest days in real estate when he worked for his father, Fred, and involve partnerships set up with his siblings (such as the East 61st Street Company, Reg Tru Equities and Park Briar Associates). Some don't really look like businesses (membership on the board of the Police Athletic League); some are whimsical (a carousel he operates for New York City); some seem to describe the current political moment (Trump Follies LLC).

Some of Trump’s businesses also appear to be in countries that don't necessarily sync up with the candidate's foreign-policy message. There's DT Marks Dubai, DT Dubai Golf II Manager, THC Jeddah Hotel Manager and THC Qatar Hotel Manager, which are all in the Muslim world. And then there's THC China Development, THC China Technical Services and THC Shenzhen Hotel Manager, all in a country Trump has whipped with gusto.

Regardless of their size, location or profitability, there is nothing to stop a President Trump from exercising control over these enterprises from the White House.

Federal conflict-of-interest laws dating from the Civil War era prevent unelected officials who work in the executive branch from collecting income from outside businesses and in government decisions that might affect their private financial interests. But Congress originally exempted itself, the president, the vice president and federal judges from such strictures, on the theory that a broad conflict-of-interest law might dissuade merchants, farmers and other businessmen from joining and leading the government.

Congress added an extra layer of reasoning to the chief executive. Presidents were exempt because the office's powers were so expansive as to make any conflict law meaningless. Every executive action would carry with it the possibility of conflict. It was best, therefore, to trust the person in charge and not create strictures that could prevent a president from acting at full constitutional capacity.

Congress consolidated a variety of conflict-of-interest guidelines in 1962 and then updated them with passage of the Ethics in Government Act in 1978. Pushed through Congress after the Watergate scandal, the law, among other things, imposed some outside income restrictions on members of Congress and spelled out a new series of restrictions that might make elected and unelected officials unable to perform their jobs impartially. (No big aerospace investments for the secretary of defense, for example.)

For the first time, it also required presidents to publicly disclose assets and business interests.

Government officials can retain their assets by placing them in a blind trust controlled by
a fully independent manager. The 1978 act formalized this practice, and also created the Office of Government Ethics to monitor conflicts of interest. (While the OGE was designed to be independent of the executive branch and is staffed with civil servants, the president still gets to appoint the person who runs it.)

Because presidents remain exempt from conflict-of-interest statutes, the blind trust is essentially ceremonial -- a tradition but not a requirement. Nevertheless, it's been a tradition recent presidents have followed. Lyndon B. Johnson and his wife put their Texas radio holdings in a blind trust. Jimmy Carter, Ronald Reagan, both of the Bushes and Bill Clinton did the same with their assets. Barack Obama, who mostly owns mutual funds and Treasury notes, has opted to skip a blind trust since, his argument goes, there’s little he can do to influence the performance of his relatively basic portfolio.

But Donald Trump would represent something entirely new in the White House. He would arrive comfortably wealthy, as others have before him (a number of the Founding Fathers were land-rich, while Theodore Roosevelt, Franklin D. Roosevelt and John F. Kennedy were scions of wealthy families. On an inflation-adjusted basis, George Washington and JFK may have been the wealthiest presidents ever.

Unlike those men, however, Trump has been a hard-driving businessman his entire adult life and he’s been actively involved in a grab bag of enterprises -- a portion of which appear to be global. (Disclosure: I wrote a Trump biography, “TrumpNation,” for which Trump sued me in 2006 because, among other things, it questioned the size of his fortune. The suit was later dismissed.)

In addition to operations in China and the Middle East, Trump's campaign disclosures show companies that appear to run licensing, hotel, golf and other businesses in Azerbaijan, Brazil, Egypt, Georgia, India, Indonesia, Israel, Philippines, South Africa and Turkey.

Federal conflict-of-interest laws would still prohibit Trump from using his presidential powers to the advantage of his businesses or the financial interests of other family members, but it would be hard to conceive of any major global trade deal that wouldn't raise a red flag given Trump's international presence. Other geopolitical and national security policies could also intersect with Trump's overseas enterprises. His domestic real estate businesses would be affected by shifts in interest rates and tax policies, and he owes at least several hundred million dollars to banks that his administration would regulate.

Here's another area that's ripe for confusion and potential conflicts of interest: Trump has said that three of his children -- Donald Jr., Ivanka and Eric -- would run the Trump Organization if he's in the Oval Office. But that trio -- ages 38, 34 and 32, respectively -- hardly represents a disinterested managerial corps. It would be reasonable to assume that they would probably be in close contact with their father about the family's multiple business and political affairs. (The Office of Government Ethics forbids family members from overseeing blind trusts for members of the executive branch.)

Trump presents an added complication. He has said for years that he believes that a large part of his fortune is tied up in the value of his brand, which he has never been shy about promoting. Recall that it was only a few months ago that Trump turned a news conference following three of his primary and caucus victories into an infomercial in which he touted the virtues of Trump Water, Trump Wine and Trump Steaks (Trump's steak business is actually defunct and he was displaying another company's product). So it's worth pondering whether Trump might turn the White House into his own version of Wal-Mart.

"We are at an entirely different order of concern than we've had in the past," says Noah Bookbinder, executive director of the nonpartisan watchdog group Citizens for Responsibility and Ethics in Washington. "You could see where Trump's actions as president could have a significant impact on that brand."

To allay such concerns, Trump could take a page from the late Nelson Rockefeller, who was an heir to a fortune and industrial empire far more substantial and consequential than anything Trump has ever overseen. In order to get confirmed as Gerald Ford's vice president in the wake of Richard Nixon's 1974 resignation, Rockefeller sat through congressional hearings in which strangers scoured his family's business dealings and finances.

“My sole purpose is to serve my country," Rockefeller told his Senate inquisitors at the time. "I would not be influenced by so-called interests.”

Can we expect the same from Trump? Well, in more than four decades in business, Trump has prided himself on stretching, not following, rules. "The Outlaw archetype loves to break the rules," Trump once advised aspiring entrepreneurs in "Midas Touch," his 2011 book. "The motto of the Outlaw is: 'Rules are meant to be broken.'"

This column does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.