Below is my column in USA Today on the role that statements from both President Barack Obama and Donald Trump could feature greatly in the unfolding litigation over the rescinding of the DACA order.  Ironically, it will be the opposing sides relying on the respective statements from these presidents.

Here is the column.

For Justice Department lawyers, this week must have a maddening familiarity.

The lawyers are in court defending President Obama’s Deferred Action for Childhood Arrivals program. They are also looking at a challenge by New York Attorney General Eric Schneiderman and others to President Trump’s rescission of DACA.

Key to both cases is the doctrine of the separation of powers. Tuesday, the administration staked out the position that DACA was constitutionally flawed as a circumvention of the legislative branch. However, that position was less than 10 hours old when Trump posted a tweet that directly contradicted the legal position of his own administration. Trump suggested that he might reissue DACA or a similar program if Congress does not act — effectively same position as Obama.

It was an all-too-familiar position for the Justice Department. Earlier this year, presidential tweets and comments directly contradicted arguments being used to defend Trump’s immigration ban in court. Those tweets were then used by various courts in rulings against the administration.

However, there is a twist this time. The expected litigation over DACA’s rescission could feature not one but two presidents as witnesses against their own positions: Trump and Obama.

After Attorney General Jeff Sessions quoted from my prior work on the separation of powers in his announcement rescinding DACA, I have certainly heard from many angry people who were aghast that my work would support such a result. It does. As a Madisonian scholar, I believe strongly in clear lines of separation of powers and the need to restore legislative authority after years of unilateral presidential actions. I also happen to support protections for “dreamers,” whose parents brought them here illegally when they were young children. In the end, it was not the merits but the means behind Obama’s program that ran afoul of the Constitution. Regardless of how one feels about amnesty programs, Trump returned DACA to the place it should have remained: in Congress.

Sessions laid out that principled position in favor of the legislative process mandated by the Framers. Yet no sooner had the attorney general explained that position when the president tweeted, “Congress now has six months to legalize DACA (something the Obama administration was unable to do). If they can’t, I will revisit this issue!”

The tweet was widely interpreted to mean that Trump is prepared to do exactly what Sessions said was unconstitutionally done by the Obama administration: Issue an executive action to protect DACA immigrants.

It is hard to see how “revisit” does not mean “reissue.” If so, the tweet undermines the position of the administration in court over DACA and takes away constitutional high ground claimed by Sessions. In the pending litigation, plaintiffs can now argue that DACA is not really dead, and that the president was not serious about leaving it entirely to Congress.

Likewise, any challenge by Schneiderman and others can now cite the tweet as evidence that the separation of powers concerns were not the motivation for the president. Rather, they will argue that Trump, like Obama, has suggested that he could order the same relief if Congress does not yield to his demands.

The tweet also undermined the legislative strategy of the administration. The pressure to get Congress to act seemed to be working after Sessions’ announcement. Many Republicans saw the political costs of the termination of DACA as worse than the costs for passing some protection for these individuals. As soon as that pressure seemed to be motivating members toward action, the tweet reduced that pressure by suggesting that Trump would not allow the program to truly die.

Conversely, Schneiderman and the challengers have their own inconvenient presidential statements to contend with. Some expect challengers to bring a case under the Administrative Procedure Act as a “substantive” (or “legislative”) rule requiring a notice-and-comment period. Putting aside that the rule does not require such a process for “interpretative rules, general statements of policy, or rules of agency organization, procedure, or practice,” Schneiderman and his other challengers never went to court to challenge DACA itself on the same grounds. DACA notably did not go through notice or comment.

Finally, not only can the Justice Department argue that the procedural rule does not apply to a president as a non-agency, the memo creating DACA stated, “This memorandum confers no substantive right, immigration status or pathway to citizenship.”

Likewise, where Trump’s tweets and comments are likely, again, to feature prominently in litigation, Obama’s statements are likely to be equally problematic for challengers. Some challengers are suggesting that DACA may be permanent because of the “estoppel doctrine” — arguing that dreamers relied on the government promise that they could remain.

However, in his issuing of the DACA order, Obama expressly stated that it is “not a permanent fix. This is a temporary stopgap measure.” Obama also said he could not change federal immigration law through his executive orders.

Thus, Obama and his administration are on record undermining claims under both the procedural rule and estoppel. Ultimately, the challengers will be in the unenviable position of arguing that Trump’s rescinding DACA requires notice and comment when Obama’s implementation of DACA did not.

Moreover, challengers are suggesting that Obama had inherent presidential authority to bar the enforcement of federal law, but that Trump cannot use the same authority to enforce it. Finally, they will have to argue that people already in this country unlawfully have an enforceable promise despite Obama saying that he could not change the law or make any permanent promises.

The deepening uncertainty over presidential statements and the status of DACA only reinforces the wisdom of the Framers in forcing such major decisions into the legislative process. What we need is additional legislation, not proclamations. Otherwise, the upcoming litigation is going to get awfully confusing.

Jonathan Turley, the Shapiro Professor of Public Interest Law at George Washington University, is a member of USA TODAY’s Board of Contributors. Follow him on Twitter @JonathanTurley.