WHEN CRIME numbers go up, it is generally cause for alarm, but the District’s 51 percent increase in the number of reported sexual abuse cases between 2011 and 2012 may be reassuring — a sign that D.C. police are taking more seriously complaints of sexual assault. Is further improvement needed, as argued in a new, highly critical report? That’s not clear, which is why Police Chief Cathy L. Lanier is prudent to ask the Justice Department to independently review the District’s handling of these cases. The D.C. Council should also take a look.

The report, by the advocacy group Human Rights Watch, concludes that victims of sexual assault in the District are not getting the effective response they are due from the Metropolitan Police Department. The 197-page report alleges that 170 reported cases of sexual assault went uninvestigated between 2008 and 2011 and that women bringing the complaints often received callous, traumatizing treatment. Chief Lanier challenged many of the group’s conclusions, contending that it used flawed methodology and overlooked recent reforms. Not only has the police department changed personnel but also, as The Post’s Peter Hermann reported, Ms. Lanier has made a priority of investigating sexual assaults, particularly those involving acquaintances.

So it’s to her credit that, notwithstanding her criticism of the Human Rights Watch report, Chief Lanier acknowledged the usefulness of some of its suggestions and moved to put them in place, including adding staff members to the sexual-assault and victim-service units and making treatment of victims a factor in how detectives on the assault unit are evaluated. She also announced the creation of a Web site where victims who think their cases were mishandled during this disputed period can file a grievance.

Such responses are more useful than the unfortunate rhetoric that has marked the increasingly hostile exchanges between Chief Lanier and Human Rights Watch. Chief Lanier may be correct that the group is out to get publicity; Human Rights Watch may be right that Chief Lanier is too defensive. They both ought to recognize that they share common goals: of ensuring that all allegations of sexual abuse are thoroughly investigated and that the effects of this awful crime on victims are never forgotten or minimized.