Comment by bubblethink

No, you are confusing discretion with whims of the executive branch. Consular officers have discretion to adjudicate the applications and they can deny them for reasons prescribed in the INA. Those decisions are not reviewable. They are still supposed to follow their training, the FAM, and the INA in making the decisions. If Rubio sends an email to the consulates that says, "deny all visas", that would be illegal as a matter of policy and will be overturned by the courts under the APA. Note that 212(f) (aka Muslim ban from Trump v. Hawaii) gives discretion to the president to bar entry into the country, not visa adjudications. Visa adjudications require individualized determination by the consular officer.