Tournament: Greenhill | Round: 2 | Opponent: Jacob Elliott | Judge: Erick Berdugo
I negate. 

I define ought as moral obligation.

Larry Diamond, Senior Fellow at the Hoover Institution, Stanford University, and founding co-editor of the Journal of Democracy.What is Democracy? Lecture at Hilla University for Humanistic Studies (January 21, 2004) defines democracy with four points. 

“First, A political system for choosing and replacing the government through free and fair elections....

The value is morality per ought in the resolution.

Moral obligation stems from reasons.
Velleman, J. David. "A Brief Introduction to Kantian Ethics." Self to Self. Cambridge University Press (New York, NY; 2006) (2005): 16-44.

So, moral obligations come from requirements internally imposed by reason.

Since morality should be normative, moral reasoning must subjectively universal. Stephen Engstrom. Professor of Philosophy at the University of Pittsburgh. Universal Legislation as a Form of Practical Knowledge. 

Morals can only be formed when people can freely reason about what their morals are.
Rational  people will universally agree to freedom because it allows them to pursue their ends.

Arthur Ripstein. Professor of Law and Philosophy at the University of Toronto. “Beyond the Harm Principle.” 2006.

freedom is understood as each person’s ability to set and pursue his or her own purposes, consistent with the freedom of others to do the same...

Thus, the criterion is promoting freedom. 

Observation: while it is true that certain freedoms are abridged under a government, there always exist a positive obligation to do so. For example, I ought to stop at a red light because not doing so puts another driver in danger. Thus, absent an adequate moral duty to abridge freedom, freedom of choice ought to prevail. 

C1. Compulsory voting forces politics into the lives of citizens. 

In a compulsory voting system, it is presupposed that
CV raises turn out by compelling people to go to the polls using various forms of sanctions.
CV raises political awareness as people have to vote whether informed or not.

But this process opens up for the unnecessary intrusion of politics into private life.
Schäfer, Armin. "Republican liberty and compulsory voting." (2011).

Schäfer2

reedom begins where politics ends...

Moreover all this hardly makes a different as the current voters already accurately represent collective interest. 

Schäfer 3

..conclude that non-voters do not form a homogeneous group and that an increase in turnout would hardly make much of a difference. 

Wherein universal voting has no instrumental value to justify the coercion it entails, and violates freedom, voting ought not be compulsory.

C2: The duty to vote is not universal, so it cannot be a moral obligation

Lever, Annabelle (2008) 'A liberal defence of compulsory voting': some reasons for scepticism. Politics, 28 (1). pp. 61-64. ISSN 0263-3957 

Even if a duty exists, it only extends to people who are interested in self government through voting in public elections. 

W. H. Morris Jones, London School of Economics and Political Science, 1954, "In Defense of Apathy: Some Doubts on the Duty to Vote," Political Studies, Vol. II, No. 1, p. 33-4
The duty to vote may, in the first place, be a duty to oneself....