Numerous Members of Congress, political observers and disappointed supporters have criticized President Barack Obama for failing to change many of the now-common practices of presidents to expand executive powers.

Whether the initiation of military engagement in Libya without Congressional consent or a variety of secrecy practices, the president has acted on a number of occasions in ways that enable him to direct policy without engaging in the deliberative process with lawmakers.

Signing statements are among the devices of direct presidential action that avoid accountability and thus have resulted in strong criticism of this president. At the end of 2011, and right in the midst of the holiday season, Obama appended lengthy signing statements to two major bills he had signed into law, resulting in a new round of allegations of a presidential power-grab made when least likely to generate any immediate public notice.

It is especially tempting to criticize Obama for such actions because, as a candidate for the White House, he promised a higher standard of conduct than that practiced by his predecessors. Longtime observers of the modern presidency should not be surprised though, as it is predictable that when a new president sees the utility of a particular power established by his predecessors, he is not going to give it away. On several occasions now, what Obama has not been able to achieve through the normal ebb and flow of deliberations with the legislative branch, he has stipulated through the issuance of a signing statement.

On Dec. 23, the president signed into law an omnibus year-end spending bill. He then issued a signing statement that declared that some provisions of the bill he had signed were either unconstitutional or had infringed on executive powers. In issuing his signing statement, Obama objected to certain provisions that may “violate constitutional separation of powers principles” and declared that he would “interpret and apply them in a manner that avoids constitutional conflicts.”

Obama’s signing statement effectively nullified provisions of the bill that limited his flexibility in dealing with prisoners at Guantánamo Bay, Cuba. It also overrode provisions that mandated presidential consultation with Congressional committees before authorizing military exercises costing above a specified amount or that required Congressional approval before U.S. forces could operate under command of the United Nations.

Eight days later, Obama signed into law the fiscal 2012 defense authorization measure. In so doing, he issued another signing statement, this time excising from the law provisions that he claimed violated core executive responsibilities. One provision, for example, forbids the use of appropriated funds for the purpose of transferring Guantánamo detainees to be tried in U.S. federal courts. Obama objected that the provision “does not serve our national security. Moreover, this intrusion would, under certain circumstances, violate constitutional separation of powers principles.” He went on to note that numerous provisions of the law conflicted with his “constitutional foreign affairs powers” and that he would treat such provisions as “non-binding.”

The White House and Congress had struggled for several months over various provisions in this bill. Obama threatened to veto the legislation if Congress did not remove certain objectionable portions.

What Obama could not achieve through these lengthy negotiations with Congress he mandated unilaterally in his signing statement. And some Members of Congress have publicly objected that the president’s signing statement even removed provisions that had been worked out in negotiations between the branches and that Obama had promised to lawmakers in order to secure their votes on the bill.

Obama might or might not be right that certain provisions of legislative enactments violate presidential authority or principles of separation of powers. Such weighty issues are appropriate for resolution through a process of deliberation and accommodation between the political branches. Signing statements that attempt to change law are the kind of unilateral presidential actions that strike a serious blow against the core principles of separation of powers and the rule of law, especially when the president acts to nullify agreements with Congress that made passage of a bill possible in the first place.

Candidate Obama adopted the constitutionally correct position in 2008. He directly criticized his predecessor for changing “what Congress passed by attaching a letter saying ‘I don’t agree with this part’ or ‘I don’t agree with that part.’” Candidate Obama correctly added, “Congress’ job is to pass legislation. The president can veto it or he can sign it.”

President Obama, though, has acted differently in this area and much more in line with the predecessor he had criticized than with his own campaign promise.

Jeffrey Crouch is assistant professor of American politics at American University. Mark J. Rozell is professor of public policy at George Mason University. Mitchel A. Sollenberger is assistant professor of political science at the University of Michigan-Dearborn.