President Obama has used memos to change immigration law. But now he's using his presidential pen for a different reason -- to express a preference for antibiotic free meat and poultry.

"The Administrator of General Services, in consultation with the Secretary of Agriculture, the Secretary of Health and Human Services, and the Director of the Office of Management and Budget (OMB), shall take the following steps to make meat and poultry produced according to responsible antibiotic-use policies available in Federal cafeterias that the General Services Administration (GSA) manages (GSA cafeterias)," the Obama memo reads.

within 120 days of the date of this memorandum, GSA shall initiate a process in which vendors, under new contract awards (including renewals), offer in GSA cafeterias, as an option, meat and poultry from animals that have been raised according to responsible antibiotic-use policies, to the extent such an option is available and cost effective. ... [E]xecutive departments and agencies (agencies) that contract for food in their own cafeterias and make meat and poultry produced according to responsible antibiotic-use policies available in their own cafeterias, may choose to similarly submit customer demand, product supply, and market price information to the Director of OMB and the Task Force, subject to the requirements of this section and under their own authorities.

And the president is setting a timeline. "Broadening the Availability of Meat and Poultry Produced According to Responsible Antibiotic-Use Policies in Federal Cafeterias. By 2020, each agency shall develop and implement a strategy that creates a preference for awarding contracts to vendors that offer, as an option, meat and poultry produced according to responsible antibiotic-use policies for sale in domestic Federal cafeterias to civilian Federal employees and visitors, to the extent such an option is available and cost effective."