Michael Geist has an article in this month's First Monday which refutes record industry excessive claims regarding file sharing's effects on music sales. Here's the abstract:

Canada is in the midst of a contentious copyright reform with advocates for stronger copyright protection maintaining that the Internet has led to widespread infringement that has harmed the economic interests of Canadian artists. The Canadian Recording Industry Association (CRIA) has emerged as the leading proponent of copyright reform, claiming that peer–to–peer file sharing has led to billions in lost sales in Canada.

This article examines CRIA’s claims by conducting an analysis of industry figures. It concludes that loss claims have been greatly exaggerated and challenges the contention that recent sales declines are primarily attributable to file–sharing activities. Moreover, the article assesses the financial impact of declining sales on Canadian artists, concluding that revenue collected through a private copying levy system already adequately compensates Canadian artists for the private copying that occurs on peer–to–peer networks.