when donald j. trump takes office on jan. 20, he will have immense but not unlimited power at his disposal. back in june, i wrote that he could <u+2014> even without congressional consent <u+2014> execute much of his vision. he could, for example, shift enforcement priorities against unauthorized immigrants, probably bar muslims from entering the country, raise tariffs, withdraw forces from the middle east, and tear up trade treaties and military alliances. but there were limits: he could not build a border wall without a congressional appropriation, impose the death penalty on killers of police officers, or strengthen libel laws so that he could sue newspapers that criticized him. that was then. because mr. trump enjoys republican majorities in both houses of congress, his power is even greater. if he can get republican members of congress to go along with him, he can do pretty much anything not banned by the constitution. he can repeal obamacare, cut taxes and build his border wall. but limits remain. one barrier is the filibuster in the senate. since they compose nearly a majority of the senate, democrats can use the filibuster to block legislation they oppose. unfortunately for democrats, however, the filibuster is not as powerful as it once was. in 2013, senate democrats eliminated the filibuster for federal appointments <u+2014> except supreme court justices <u+2014> in an effort to stop what they saw as obstructionism by the republican minority, who repeatedly blocked president obama<u+2019>s nominations. <u+201c> you<u+2019>ll regret this ,<u+201d> the senate republican leader mitch mcconnell warned the democrats. he was right. democrats now can<u+2019>t stop trump from appointing anyone acceptable to republican senators. and citing this precedent, republican senators may eliminate the filibuster for supreme court justices as well, giving mr. trump a nearly free hand to appoint whom he wants. another barrier is the courts. president obama has appointed hundreds of federal judges over his two terms, and hundreds of others <u+2014> including republican appointees <u+2014> will view with skepticism some types of unilateral executive action that mr. trump has promised. it would not be surprising if judges blocked or at least slowed an aggressive roundup of unauthorized immigrants (though they did not stop president george w. bush<u+2019>s roundup of muslims and arabs after sept. 11). while the law gives mr. trump power to withdraw regulations and refuse to enforce them, courts that distrust his methods or motives may create procedural stumbling blocks, just as they did to president obama<u+2019>s plan to grant work permits and other privileges to a group of unauthorized immigrants. but the courts, too, possess only limited powers. they typically refrain from interfering with the president when he engages in military operations and diplomacy. it is hard to imagine them standing in the way if he tears up treaties or transfers military forces hither and yon. with the passage of time, president trump will be able to place his people in the judiciary, and trumpian judges will see things his way. history shows that a president can usually depend on his supreme court appointee (or appointees) to support him if he is challenged. the greatest constraint on mr. trump may be the federal bureaucracy. if he directs the f.b.i., i.r.s. or department of homeland security to harass his political opponents, civil servants will probably not cooperate <u+2014> indeed, they may blow the whistle. president bush faced threats of resignation by justice department officials over his surveillance program and leaks about his policy of coercive interrogation. mr. obama had to put up with damaging leaks from federal employees and contractors who opposed his surveillance programs. but many in the bureaucracy <u+2014> in the military and at immigration agencies in particular <u+2014> support mr. trump and may follow his policies enthusiastically. and because his agenda is mostly deregulatory, he possesses most of the cards. he can delay or block new financial, environmental and workplace-safety regulations without the cooperation of agency officials; he can probably block enforcement of them as long as he is able to appoint loyalists to leadership positions. the news media will also play a role in constraining mr. trump. his threats to strengthen libel laws are idle. the first amendment protects the media, and today <u+2014> unlike in the past <u+2014> that amendment is a darling of republican jurists. but the media can constrain mr. trump only to the extent that it can rouse public opinion against him and his policies. this may involve showing sensitivity to middle american sensibilities that it has not always demonstrated. in the end, the success of mr. trump<u+2019>s administration depends on mr. trump himself. if he shows self-discipline, which was conspicuously lacking during the campaign, and hews to relatively moderate center-right policies, he may be able to accomplish a great deal (for good or ill). if he insults large groups of americans, uses his powers to unleash vendettas against his opponents, places political hacks in the bureaucracy, and betrays allies, he will fail. it<u+2019>s his choice. eric posner is a professor at the university of chicago law school and a co-author of <u+201c>the executive unbound: after the madisonian republic.<u+201d> follow the new york times opinion section on facebook and twitter , and sign up for the opinion today newsletter .
are there limits to trump<u+2019>s power?
eric posner