On the face of it, a policeman shooting a young man who was walking away after threatened the law officer and his colleagues with a knife sounds like an error of judgement. That error seems all the greater when the policemen actually fired no less than 16 times, killing the knife-wielding youngster. And then comes the most difficult part about the knifeman's killing in Chicago in 2014. The dead young man was black. The lawman who shot him is white. That police officer, Jason Van Dyke, is now on trial in Chicago charged with first degree murder. This latest police killing triggered yet another in a series of protests, not confined simply to the black community, against what is seen as a rising tide of police brutality aimed at racial minorities in general and the black community in particular. Yet the problem with popular outrage is that it is so often ill-informed and driven not by the facts but by emotion. In truth, Van Dyke's slaying of Laquan McDonald was one of an appalling record 626 killings by US law enforcement officers in 2014. This year, however, the figure is likely to be near 374. The previous peak had been 602 in 2012. In 2010 there had been just 63 deaths at the hands of the police. So, therefore, liberal roars that police killings are reaching crisis proportions are just plain wrong. These tragedies, not just for the victims but for the officers who pulled the deadly triggers, may in part be motivated by racism, as is being claimed. However, black police officers are also shooting dead black suspects. The problem is clearly much deeper. When it comes to firearms, the United States is ruled by fear. The virtually unrestricted possession of weaponry is enshrined in the nation's constitution. The right to bear arms was never supposed to endorse the right to use them to destroy fellow citizens. It is often overlooked that when a US law enforcement officer goes into action, even when stopping a motorist for a minor traffic violation, it is necessary to be prepared to be threatened by a legally-held weapon which is often far more powerful and deadly than anything that the police officer concerned can deploy. On videos of traffic stops on US reality cop shows, it almost seems ludicrous that the police officer is unbuttoning the pistol holster while approaching a vehicle whose driver may have committed something as trifling as exceeding the speed limit by a few kilometers an hour. Yet that is the way of things in an America which is now seeing almost one mass killing every day. It is hard to blame US law enforcement officers for their near terror in such an anarchic situation. Poorly-trained and relatively badly-paid, they have subscribed to an insidious culture of firing first and asking questions afterwards. It seems that all too often, the slain suspects did not represent genuine danger to the arresting officers. But how were the cops to know that in the split seconds it took to decide to fire? And there is something else that liberal pressure groups choose to ignore in this law enforcement horror story. The majority of the people who get fired on have been recklessly brandishing some sort of weapon. Their guilt is not diminished by their being shot dead.