Last week, former Presidents Barack Obama and George W. Bush reappeared in the political limelight with public speeches. While never specifically naming President Donald Trump, many observers saw the speeches as rebukes of the current administration.

Obama, who was campaigning in New Jersey for gubernatorial candidate Phil Murphy, spoke about rejecting the "politics of fear" that existed in the country. His speech, while directed at Democrats, argued that the nation was witnessing political division that is worse than 50 years ago. This follows Trump's decision to attack Obama-era reforms such as the Paris climate accords and the Affordable Care Act.

Bush delivered a similar message, speaking in New York at the "Spirit of Liberty: At Home, In the World" event. The Republican ex-president spoke about the presence of bigotry and white supremacy in the nation, and the idea of "nationalism distorted into nativism." During the presidential campaign, Trump frequently criticized Bush's decision to embark on the Iraq War.

The actions of Obama and Bush are uncommon, as former presidents tend to avoid criticizing the decisions of their successors directly. With a White House that has challenged the boundaries of a traditional presidency however, it raises debate on the role of ex-presidents in the trajectory of U.S. politics.

We spoke to Robert Spitzer about the dilemmas ex-presidents face and their political relationships with their successors. Spitzer is Distinguished Service Professor of Political Science at the State University of New York College at Cortland and author of four books on the presidency.

What is the role of the president after he leaves the office?

In general, former presidents are generally seen as elder statesmen who tend to not become involved in normal politics, but instead stay above the fray. Sometimes they become involved in charitable or non-profit foundation work, or simply retire from active public life.

Do they have a right to rebuild their reputation or approval ratings after they leave the office?

Former presidents certainly can do what they want to try and improve their reputations if they have suffered -- best examples include Herbert Hoover and Richard Nixon, both of whom worked to rehabilitate themselves after their troubled presidencies. Jimmy Carter did not suffer the kind of disgrace that someone like Nixon did, but his presidency was viewed by many as not very successful. He founded his own very active Carter Center which has worked in many humanitarian efforts, such as eradicating the guinea worm in Africa, negotiating peace in troubled nations, and other similar activities. Carter has been one of the most successful former presidents.

Have presidents spoken out in the past, or is there an unspoken code of silence?

It is rare for former presidents to speak out specifically about a current administration. There is no recent precedent I can think of where former presidents were this detailed and specific in their criticisms of a current president, especially so early into Trump's term.

Can former presidents comment on the presidency of their successors? If they are to do so, are their arguments undermined if they never name the president?

Well, there is nothing preventing former presidents from speaking out, and it is a free country, so they cannot be stopped. There is a kind of unwritten code, though, that former presidents not inject themselves into current political controversies directly. But no, their arguments are not undermined if they don't actually mention the current president who they are criticizing. There is no doubt that Obama and Bush II were criticizing Trump, even though they did not mention him by name.

Are the speeches by Obama and Bush directly targeted at the Trump administration, or are they reflections of greater issues in society?

It is both. Recent criticism have focused both on Trump's personal style and personal actions, but also on his policies, which many have come to view as too draconian, too harsh, and too heavily weighted toward a few special interests.

Should current administrations be allowed to speak out against their predecessors?

Again, current presidents have every right to respond if they so choose. I do think it is bad form for a sitting president to be so specific and cutting in such comments, but Trump has invited and paved the way for the lowering of our national discourse going back to the 2016 campaign. Presidents usually put the sharp partisan tone of the election behind them after they are elected. But Trump is the first president to not only maintain a partisan and negative tone, but to even increase it against anyone who criticizes him. Frankly, by his words and deeds, he has invited this criticism.