There's no way to know for sure. If it was clearly illegal and Facebook's lawyers thought they were going to lose they'd settle with the IRS. If it clearly wasn

There's no way to know for sure. If it was clearly illegal and Facebook's lawyers thought they were going to lose they'd settle with the IRS. If it clearly wasn't illegal the IRS wouldn't pursue the case. The courts are needed in the fuzzy area to interpret the law and answer the question - was it actually illegal? Other alternatives: If, for example, the IRS has been pressed into the case by public or political pressure they may pursue an unwinnable legal case to win in the court of public opinion or to give other corporations with fewer legal resources than Facebook pause before they engage in similar.