President-elect Donald Trump and Vice President-elect Mike Pence emerge with education secretary nominee Betsy DeVos after a meeting at Trump National Golf Club’s clubhouse in New Jersey on Nov. 19. (Mike Segar/Reuters)

As Donald Trump begins to assemble a White House, his process has resembled his campaign for president: unconventional and controversial. Several of his initial picks — Stephen K. Bannon as an adviser, Michael Flynn as national security adviser, Jeff Sessions as attorney general — have drawn attention for statements that disparage racial and religious minorities, including Muslims, Jews and African Americans.

But once he is finished, will Trump’s Cabinet fully exemplify his proclivity for rule breaking? Our research into seven parliamentary and presidential democracies (including the United States) shows that even if presidents enjoy wide latitude in cabinet appointments — beyond prohibitions on appointing family members and the requirement of Senate approval — there are many unwritten, but nonetheless important, rules. The big question is how much Trump will follow them.

There are three rules for cabinet appointments

The first two rules are straightforward. Cabinet ministers must have educational credentials or experience in government or the private sector that is seen as relevant for their post. A nominee like Sessions, however controversial, has both education credentials and relevant government experience (in his case, a law degree and experience as a U.S. attorney).

Similarly, Betsy DeVos — Trump’s nominee for secretary of education — has experience in education reform, particularly the charter school movement. Again, her selection is not without controversy, but she has some relevant experience.

A second rule is likewise straightforward: Presidents and prime ministers appoint cabinet members whom they can trust and who have demonstrated loyalty to them (or to their party). Our research shows that friendship and personal relationships powerfully predict cabinet appointments. This is clearly true for Trump: Many of his initial appointments at both the Cabinet and sub-Cabinet levels are to people who endorsed him, such as Sessions, or advised him during the campaign, such as Flynn.

The third rule is different: Cabinets should “look like” the country in some way. Citizens expect cabinets to be representative of them and of their interests. All presidents and prime ministers consider representation, but the rules about who is represented, and how many representatives are necessary, vary. In some countries, like Canada, regional representation matters greatly, but in the United States it does not.

However, there is one group that matters in all the countries we studied: women. In some countries, such as Germany and Spain, cabinets come close to being evenly balanced between men and women. In other countries, such as Britain, women tend to make up a substantial minority of cabinet positions. Either way, each country has what we refer to as a “concrete floor”: a minimum number or proportion of women believed necessary for a cabinet to be perceived as legitimate. Concrete floors matter because regardless of which party wins office, a minimal threshold of female appointments is generally predictable, and because selectors generally adhere to the standard set by their predecessors.

How frequently are women appointed to the Cabinet in the U.S.?

In 1933, President Roosevelt appointed the first woman to the Cabinet, Frances Perkins, as secretary of labor. Thereafter, however, many Cabinets had no women. The last president to appoint only men to his initial Cabinet was Ronald Reagan.

Since then, presidents have been attentive to including women as well as members of racial or ethnic minority groups. Indeed, every president since 1975 has included at least one woman in his Cabinet, without exception, and there have been no all-white Cabinets since Richard Nixon left office. This is true for Democratic and Republican presidents alike.

Since 1993, every president has included at least three (and occasionally more) women in his initial Cabinet, regardless of his party. Clinton appointed four women in his second term (and five total across his presidency). Clinton’s successor, George W. Bush, had three female appointees in his first term and four in his second. Barack Obama appointed four women in his first term and, eventually, another four in his second term.

Will Trump follow this representational rule on gender? Because men are disproportionately overrepresented in the Republican Party leadership and in Congress, some say it would be difficult for Trump to find enough women.

Our research suggests otherwise, however. Appointing to the standard of the concrete floor is relatively easy. Trump needs to appoint only three or four women to Cabinet secretary positions to match his Republican and Democratic predecessors. He has already begun, by appointing DeVos, and there are other possible women to nominate.

Breaking rules can be costly

We find that there are sanctions for presidents and prime ministers who violate the informal rules of cabinet appointments. There can be intense media scrutiny and public criticism of an appointee’s performance. In the worst cases, there may be enough dysfunction to provoke cabinet reshuffles or replacements.

There are also hidden costs to presidents and prime ministers who violate informal rules about gender or racial diversity. Homogeneous cabinets can blind an administration to the full range of policy possibilities. They can make a chief executive unaware of approaching problems or growing opposition, including within Congress.

Conversely, if Trump follows the established rules — such as by appointing at least three women to his Cabinet — he would be able to claim, as promised in his victory speech, that he genuinely intends to “be a President for all Americans.”

Claire Annesley is professor and chair of the Politics Department at the University of Sussex. Karen Beckwith is the Flora Stone Mather Professor and Chair of the Department of Political Science at Case Western Reserve University. Susan Franceschet is a professor of political science at the University of Calgary (Canada). They are completing a book manuscript, “Cabinets, Ministers, and Gender.”