Yes, you can report it. It must be legitimate reason listed in the Y/A guidelines; not just because someone disagreed with you.
Please report abuse of the Y/A guidelines by clicking on the flag icon under the question or clicking the "Report Abuse" link next to an answer. See
http://answers.yahoo.com/info/community_guidelines.php for 20 reasons/instances where reporting a violation is appropriate. This includes "violating the question and answer format," "point gaming," "soliciting," "racist/homophobic/explicit remarks" and etc.
Also, see
http://blog.360.yahoo.com/blog-d8pH0dcoRKeB12yOcnUQp.9VCFos?p=22203 for the Y/A team's blog entry on this subject. Actually, they have a series of posts about violations.
This is a global site and it has little to do with being a "free country." There are rules to abide by which have been set by Yahoo.