(Reuters) - U.S. regulators got the green light from a federal judge to proceed with their lawsuit against a Texas man accused of running a Ponzi scheme using Bitcoin, the virtual online money system.
Trendon Shavers of Bitcoin Savings & Trust had challenged the Securities and Exchange Commission's case against him, saying the regulator had no jurisdiction to sue him because the Bitcoin investments he offered are not securities or subject to any U.S. regulation.

But U.S. Magistrate Judge Amos L. Mazzant in the Eastern District of Texas ruled on Tuesday that his Bitcoin investments "meet the definition of investment contract, and as such, are securities."

Bitcoin exists through an open-source software program. It is not managed by any one company, it is not regulated by any central bank, and its supply is controlled through a computer algorithm. Users can buy bitcoins through exchanges that convert real money into the virtual currency.

The SEC warned investors against the dangers of potential scams involving virtual currencies like Bitcoin in an alert on July 23, the same day it filed the charges against Shavers.

Tuesday's ruling could have important implications for the still murky legal world surrounding digital currencies, which is not regulated by the United States.

Bitcoin has come under greater scrutiny after U.S. authorities in May seized two accounts linked to a major operator in the Bitcoin digital market.

The judge's decision could be important for Cameron and Tyler Winklevoss, the twins who became famous after alleging that Facebook Inc founder Mark Zuckerberg stole their website idea.

In early July, they applied to the SEC for approval to launch a Bitcoin-tracking exchange-traded product known as the Winklevoss Bitcoin Trust.

The SEC alleges that Shavers essentially used money from new investors in his Bitcoin endeavor to cover withdrawals by older investors and his own personal expenses.

The agency said he raised at least 700,000 bitcoins, or $4.5 million, from investors in multiple states.

Shavers had asserted that his Bitcoin investments are not securities because Bitcoin is not money, but the SEC countered that they constituted both investment contracts and notes.

"It is clear that Bitcoin can be used as money," the judge wrote. "It can be used to purchase goods or services."

Shavers could not be immediately reached for comment.