When News Corp. and CEO Rupert Murdoch secured enough shares to buy Dow Jones & Co. four years ago, these columns welcomed our new owner and promised to stand by the same standards and principles we always had. That promise is worth repeating now that politicians and our competitors are using the phone-hacking years ago at a British corner of News Corp. to assail the Journal, and perhaps injure press freedom in general.

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At least three British investigations into phone-hacking and payments to police and others by the now-shuttered...