When the federal draft was instituted in 1863, during the depths of the Civil War, the new requirement sparked riots in New York City. Since then, the issue of whether the U.S military should conscript men -- and possibly women -- or rely on volunteers has remained a hot topic, especially during times of war. The last U.S. draft ended in 1973, at the close of the Vietnam War, but simultaneous wars in Afghanistan and Iraq again brought the controversy to the forefront in the first part of the 21st century.

Combat Readiness

Expecting people to volunteer in times of war may be unrealistic. During the Civil War, both sides found it difficult to attract and retain volunteers and eventually instituted a draft. During World War I, according to the National Archives' "Prologue Magazine," the draft added nearly 2.7 million to the U.S. military, while voluntary enlistments accounted for only about 300,000. A 2006 report from the Congressional Budget Office states that while the active Army met its recruiting goals for 2006, during the wars in Iraq and Afghanistan, the active Army, Reserve and National Guard all had difficulties meeting recruiting goals in previous years.

Shared Responsibility

A Pew research study showed that despite the country being involved in two wars, only 0.5 percent of the population was in the active military "at any given time" between 2001 and 2011. While the CBO found no over-representation of minorities either serving or dying in the military as of 2006, the concern remains that low-income groups may be more likely to volunteer. A draft could make service in the military more equitable among all groups. Congressional representative Charles Rangel, proposing a reinstatement of the draft in 2014, posited that with "more at stake" for all Americans, the general population would "think twice" before supporting another war.

Civil Unrest

While civic engagement can be a positive thing, a draft for a war that is unpopular with certain segments of the population, who could be forced to fight for a cause they don't believe in, can lead to wide-scale civil unrest. This, in turn, can tear at the very fabric of democracy as presidents attempt to provide a picture of a strong home front. In the case of the Civil War and World War I, protests led to suppression of free speech through the suspension of the Writ of Habeas Corpus and the Espionage Act, respectively, both used against those who interfered with the draft. During the Vietnam War, police used force against protesters outside the 1968 Democratic Convention in Chicago, and Richard Nixon's advisors eventually drew up an "enemies list" of politicians, celebrities and prominent anti-war activists, such as future Massachusetts Senator John Kerry, and targeted them for reprisal.

Professional Force

Possibly the strongest argument against the draft is that those serving in an all-volunteer military do so by their own choice. This can lead to more professionalism and more enlistees choosing the military as a career. The CBO notes that it would be difficult to require the four- to six-year initial enlistments of the all-volunteer military under a draft system. While an all-volunteer military may sometimes not bring in the numbers a draft system can, longer enlistments and a greater likelihood of re-enlistment can lead to a more professional and expert fighting force, and less dissent and desertion within the ranks.