The U.S. Department of Justice has hired former antitrust chief Sandy Litvak “for a possible court challenge” to Google’s (NSDQ: GOOG) growing advertising power, according to WSJ.  Litvack, former vice chairman of the Walt Disney Co (NYSE: DIS). and the antitrust chief during the Carter administration, has been hired to examine the evidence gathered during the review of Google’s pending deal with Yahoo (NSDQ: YHOO) and to build a case if the decision is to move forward, “lawyers close to the review” told the Journal. Those lawyers also say the DOJ has been deposing witnesses and subpoenaing information to support a challenge. If there’s a suit, it’s uncertain whether Justice would stick to the Google-Yahoo deal or expand to include other advertising activities. The paper suggests such a case could be similar to the successful Microsoft (NSDQ: MSFT) antitrust suit.