To prescribe is (1) to set down as a rule, or (2) to order the use of. Proscribe is almost the opposite; to proscribe is (1) to prohibit, or (2) to denounce or condemn.
They may both prescribe positive behaviors (e.g., be honest, transparent, candid, and trustworthy) and proscribe negative ones (e.g., no negative e-mail blasts to team members). [Forbes]
Lawyers for two of the five students said they plan to ask a court to prescribe drug treatment rather than prison. [WNYC]
Florida is one of only two states, along with Alabama, in which nurse practitioners are not allowed to prescribe controlled substances. [Orlando Sentinel]
However, despite the warning, the government decided to proscribe the export of onion. [Mid-Day]
In spite of the attempts made to proscribe them, cult activities are still on the increase. [Nigerian Observer]