A New York police commander who pepper-sprayed protesters during the opening days of the Occupy Wall Street demonstrations last month faces an internal disciplinary charge that could cost him 10 vacation days, the police said Tuesday.

The commander, Deputy Inspector Anthony Bologna, has been given a so-called command discipline, according to a law enforcement official. Officials said investigators found that the inspector ran afoul of Police Department rules for the use of the spray. The department’s patrol guide, its policy manual, says pepper spray should be used primarily to control a suspect who is resisting arrest, or for protection; it does allow for its use in “disorder control,” but only by officers with special training.

The Internal Affairs Bureau reviewed the episode and found that Inspector Bologna “used pepper spray outside departmental guidelines,” said Paul J. Browne, the Police Department’s chief spokesman. He declined to elaborate.

The inspector can accept the charge and plead guilty, or he can opt for a departmental trial. Police Commissioner Raymond W. Kelly is the ultimate arbiter of punishment in such matters and has wide leeway in his decisions.