Preface to Major Barbara by George Bernard Shaw

And now I must ask the excited reader not to lose his head on one side / or the other, but to draw a sane moral from these grim absurdities. It / is not good sense to propose that laws against crime should apply to / principals only and not to accessories whose consent, counsel, or / silence may secure impunity to the principal. If you institute / punishment as part of the law, you must punish people for refusing to / punish. If you have a police, part of its duty must be to compel / everybody to assist the police. No doubt if your laws are unjust, and / your policemen agents of oppression, the result will be an unbearable / violation of the private consciences of citizens. But that cannot be / helped: the remedy is, not to license everybody to thwart the law if / they please, but to make laws that will command the public assent, and / not to deal cruelly and stupidly with lawbreakers. Everybody / disapproves of burglars; but the modern burglar, when caught and / overpowered by a householder usually appeals, and often, let us hope, / with success, to his captor not to deliver him over to the useless / horrors of penal servitude. In other cases the lawbreaker escapes / because those who could give him up do not consider his breech of the / law a guilty action.

Sometimes, even, private tribunals are formed in / opposition to the official tribunals; and these private tribunals / employ assassins as executioners, as was done, for example, by Mahomet / before he had established his power officially, and by the Ribbon / lodges of Ireland in their long struggle with the landlords. Under such / circumstances, the assassin goes free although everybody in the / district knows who he is and what he has done. They do not betray him, / partly because they justify him exactly as the regular Government / justifies its official executioner, and partly because they would / themselves be assassinated if they betrayed him: another method learnt / from the official government. Given a tribunal, employing a slayer who / has no personal quarrel with the slain; and there is clearly no moral / difference between official and unofficial killing.