IRS was already under a legal hold order to preserve the emails

Opinion Journal:

The IRS is spinning a tale of bureaucratic incompetence to explain the vanishing emails from former Tax Exempt Organizations doyenne Lois Lerner and six other IRS employees. We have less faith by the minute that there is an innocent explanation for this failure to cooperate with Congress, but even if true it doesn't matter. The IRS was under a legal obligation to retain the information because of a litigation hold.

In 2009 a pro-Israel group called Z Street applied to the IRS for tax-exempt status. When the process was delayed, an IRS agent told the group that its application was undergoing special review because "these cases are being sent to a special unit in the D.C. office to determine whether the organization's activities contradict the Administration's public policies." In August 2010 Z Street sued the IRS on grounds that this selective processing of its application amounted to viewpoint discrimination.

Under the Federal Rules of Civil Procedure and legal precedent, once the suit was filed the IRS was required to preserve all evidence relevant to the viewpoint-discrimination charge. That means that no matter what dog ate Lois Lerner's hard drive or what the IRS habit was of recycling the tapes used to back up its email records of taxpayer information, it had a legal duty not to destroy the evidence in ongoing litigation.
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There is more.

The excuses are looking more ridiculous with each passing day.  The IRS is going to cost taxpayers even more money as it loses its litigation with entities it illegally denied tax exempt status to for political purposes.  The judges ion these cases should hold the IRS in contempt and consider striking their pleadings.