"By 'invasion' I mean the invasion of the individual sphere, which is bounded by the line inside of which liberty of action does not conflict with others' liberty of action."[675] This boundary-line is in part unmistakable; for instance, a threat is not an invasion if the threatened act is not an invasion, "a man has a right to threaten what he has a right to execute."[676] But the boundary-line may also be dubious; for instance, "we cannot clearly identify the maltreatment of child by parent as either invasive or non-invasive of the liberty of third parties."[677] "Additional experience is continually sharpening our sense of what constitutes invasion. Though we still draw the line by rule of thumb, we are drawing it more clearly every day."[678] "The nature of such invasion is not changed, whether it is made by one man upon another man, after the manner of the ordinary criminal, or by one man upon all other men, after the manner of an absolute monarch, or by all other men upon one man, after the manner of a modern democracy."[679] "On the other hand, he who resists another's attempt to control is not an aggressor, an invader, a governor, but simply a defender, a protector."[680] "The individual has the right to repel invasion of his sphere of action."[681] "Anarchism justifies the application of force to invasive men,"[682] "violence is advisable when it will accomplish the desired end and inadvisable when it will not."[683] And "defensive associations acting on the Anarchistic principle would not only demand redress for, but would prohibit, all clearly invasive acts. They would not, however, prohibit non-invasive acts, even though these acts create additional opportunity for invasive persons to act invasively: for instance, the selling of liquor."[684] "And the nature of such resistance is not changed whether it be offered by one man to another man, as when one repels a criminal's onslaught, or by one man to all other men, as when one declines to obey an oppressive law, or by all other men to one man, as when a subject people rises against a despot, or as when the members of a community voluntarily unite to restrain a criminal."[685] 3.--LAW