“Force is to be opposed to nothing but to unjust and unlawful force.”John Locke · Al doilea tratat despre cârmuire · 1689 · capitolul XIX, paragraful 204
Force that steps outside the law loses authority and becomes plain aggression.
Locke is limiting the right of resistance here: not every use of force may be met with force, only the one that steps outside the law. Legitimate government is itself a form of force authorised by law, and opposing it is not resistance but rebellion. But when a ruler acts without right, he leaves the position of authority and becomes an aggressor like any other. This is the theoretical basis for the right to remove a tyrant, which Locke develops in the rest of the treatise.
Locke flips a label we usually apply backwards. Who is the real rebel? Not the one who resists, but the one who uses force without right. A ruler acting unlawfully no longer stands for the law; he breaks it, so he rises against it first. Think of a guard who robs you: you don't become the criminal by defending yourself; he has stopped being a guard. This shifts the burden of proof: the resister need not justify himself, the one using force must. And it raises a practical question: who, in practice, decides that force has left the bounds of right?
Why it matters The idea serves anyone wondering how far obedience to authority goes: the law demands compliance, but when those enforcing it break it, criticism and opposition regain their legitimacy.