On 18 March 2013, the Financial Crimes Enforcement Network (or FinCEN), a bureau of the United States Department of the Treasury, issued a report regarding centralized and decentralized "virtual currencies" and their legal status within "money services business" (MSB) and Bank Secrecy Act regulations. It classified digital currencies and other digital payment systems such as bitcoin as "virtual currencies" because they are not legal tender under any sovereign jurisdiction. FinCEN cleared American users of bitcoin of legal obligations by saying, "A user of virtual currency is not an MSB under FinCEN's regulations and therefore is not subject to MSB registration, reporting, and recordkeeping regulations." However, it held that American entities who generate "virtual currency" such as bitcoins are money transmitters or MSBs if they sell their generated currency for national currency: "...a person that creates units of convertible virtual currency and sells those units to another person for real currency or its equivalent is engaged in transmission to another location and is a money transmitter." This specifically extends to "miners" of the bitcoin currency who may have to register as MSBs and abide by the legal requirements of being a money transmitter if they sell their generated bitcoins for national currency and are within the United States. Since FinCEN issued this guidance, dozens of virtual currency exchangers and administrators have registered with FinCEN, and FinCEN is receiving an increasing number of suspicious activity reports (SARs) from these entities.
“These companies are using extraordinary amounts of electricity – typically thousands of times more electricity than an average residential customer would use,” a spokesperson for the New York State Department of Public Service told Wired. “The sheer amount of electricity being used is leading to higher costs for customers in small communities because of a limited supply of low-cost hydropower.”
On 22 March 2011 WeUseCoins published the first viral video which has had over 6.4 million views. In September 2011 Vitalik Buterin co-founded Bitcoin Magazine. On 23 December 2011, Douglas Feigelson of BitBills filed a patent application for "Creating And Using Digital Currency" with the United States Patent and Trademark Office, an action which was contested based on prior art in June 2013.
Bitcoin is pseudonymous, meaning that funds are not tied to real-world entities but rather bitcoin addresses. Owners of bitcoin addresses are not explicitly identified, but all transactions on the blockchain are public. In addition, transactions can be linked to individuals and companies through "idioms of use" (e.g., transactions that spend coins from multiple inputs indicate that the inputs may have a common owner) and corroborating public transaction data with known information on owners of certain addresses. Additionally, bitcoin exchanges, where bitcoins are traded for traditional currencies, may be required by law to collect personal information.