Gov. Pat Quinn signed into law a measure authorizing the use of marijuana for medical purposes, as Illinois joins 19 other states and the District of Columbia in creating limited exceptions to anti-pot laws.

The "very well-drafted bill" establishing a four-year pilot program will help military veterans and others suffering from serious illnesses, the governor said during an event at the University of Chicago.

The new Illinois law includes strict limits on access to medicinal marijuana.

To qualify, a patient must be suffering from one of 42 illnesses, such as cancer, AIDS or multiple sclerosis, and have an established relationship with a physician.

Approved patients can receive a maximum of 2.5 ounces (70 grams) of pot every two weeks.

The law calls for the creation of 60 government dispensaries and 22 state-controlled cultivation centers, while prohibiting individuals from growing medicinal pot at home.

"This was for the patients," the bill's sponsor, state Rep. Lou Lang, said at the signing ceremony. "This was for the state of health care ... in Illinois." EFE