The word sanction is used both to permit an action, and to prohibit an action.
sanction
n.
5< Fr or L: Fr < L sanctio < sanctus: see SAINT6
1 the act of a recognized authority confirming or ratifying an action; authorized approval or permission
2 support; encouragement; approval
3 something that gives binding force to a law, or secures obedience to it, as the penalty for breaking it, or a reward for carrying it out
4 something, as a moral principle or influence, that makes a rule of conduct, a law, etc. binding
5 a) a coercive measure, as a blockade of shipping, usually taken by several nations together, for forcing a nation considered to have violated international law to end the violation b) a coercive measure, as a boycott, taken by a group to enforce demands: often used in pl.
6 [Obs.] a formal decree; law
vt.
to give sanction to; specif., a) to ratify or confirm b) to authorize or permit; countenance
—SYN APPROVE
sanc4tion[a[ble
adj.