Back in December 2006, the US Mint, in yet another power grab over economic life, made it illegal to melt pennies and nickels in addition to exporting large quantities of either. Though the Mint admitted there was no evidence coin melting was occurring, this was the government's attempt at being proactive to prevent the destruction of its legally imposed currency.
So why the concern over people melting down coinage that supposedly belongs to them?
Back when the ban was implemented, the high price of copper was responsible for driving up the price of individual nickels and pennies in terms of metal content. Due to their copper content (nickels minted between 1946 and 2011 are composed of 75 percent copper and pennies minted between 1909 and 1982 are composed of 95 percent copper), both coins have a higher value as metal than as legal tender.