By CHARLIE SAVAGE New York Times

WASHINGTON President Obama on Wednesday issued his first signing statement reserving a right to bypass dozens of provisions in a $410 billion government spending bill even as he signed it into law.
In the statement directions to executive-branch officials about how to carry out the legislation Mr. Obama instructed them to view most of the disputed provisions as merely advisory and nonbinding saying they were unconstitutional intrusions on his own powers.
Mr. Obamas instructions followed by two days his order to government officials that they not rely on any of President George W. Bushs provision-bypassing signing statements without first consulting Attorney General Eric H. Holder Jr. In that order Mr. Obama said he would continue the practice of issuing signing statements though with caution and restraint based only on interpretations of the Constitution that are well founded."
One of the budget bills provisions that Mr. Obama said he could circumvent concerns United Nations peacekeeping missions. It says money may not be spent on any such mission if it entails putting United States troops under a foreign commander unless Mr. Obamas military advisers so recommend.
This provision" Mr. Obama wrote raises constitutional concerns by constraining my choice of particular persons to perform specific command functions in military missions by conditioning the exercise of my authority as commander in chief on the recommendations of subordinates within the military chain of command and by constraining my diplomatic negotiating authority."
He also raised concerns about a section that establishes whistle-blower protections for federal employees who give information to Congress.
I do not interpret this provision" he wrote to detract from my authority to direct the heads of executive departments to supervise control and correct employees communications with the Congress in cases where such communications would be unlawful or would reveal information that is properly privileged or otherwise confidential."
In addition the president singled out four areas of the bill that direct negotiations with other countries on certain matters and three that issue directions about what agencies should include in budget requests.
But a majority of the challenged provisions are those allowing money to be reallocated to a different program only with the approval of a Congressional committee. Mr. Obama called the provisions impermissible forms of legislative aggrandizement" and declared that while executive-branch officials would notify lawmakers of any reallocation spending decisions shall not be treated as dependent on the approval of Congressional committees."
David M. Golove a law professor at New York University who specializes in executive powers said the prerogatives invoked by Mr. Obama were relatively uncontroversial. Still Mr. Golove said he was surprised by the scope and detail of the objections.
It reflects an executive branch that wishes to demonstrate publicly a commitment to upholding all of the presidents claimed constitutional prerogatives" he said even when the intrusions are trivial or just a matter of infelicitous wording."
Presidents began using signing statements in the 19th century but the practice became controversial under Mr. Bush who challenged more legislative provisions than all previous presidents combined.
Many of Mr. Bushs signing statements made arguments similar to those made Wednesday by Mr. Obama. But Mr. Bush invoked particularly contentious claims of executive authority as when he declared that a ban on torture violated his powers as commander in chief.
The Bush administration defended its use of signing statements as lawful and appropriate. The American Bar Association on the other hand condemned them as contrary to the rule of law and our constitutional separation of powers" and called on presidents to stop using them.
Other legal specialists have argued that there is a role for the practice so long as presidents invoke only mainstream legal theories. They say Congress sometimes includes minor constitutional flaws in important bills that are impractical to veto.