In some ways, the new U.S. Department of Justice memo on white-collar investigations standardizes in writing the same approach many prosecutors, especially big-city U.S. attorneys, have practiced all along.

But to others in Big Law and within corporations, the memo published last week — directing prosecutors to focus on individuals in addition to wider corporate wrongdoing — swings like a blunt instrument at how companies under investigation talk to officials from Main Justice, according to several former DOJ lawyers and white-collar practitioners at major law firms.