Would it be possible for Lehrmann to sue the DPP Shane Drumgold, for pursuing the matter against police advice and therefore ruining any chance of future meaningful employment for himself? Extremely Unlikely* ... It is the DPP or that office who has sole discretion as to whether a matter proceeds on indictment and as such it is the DPP that draws up the indcitment regardless of what the Police may think. The Police merely conducted the investigation. They presented a brief of evidence to the DPP who then decided to draft an Indictment.
Furthermore, each state has a governing Act, in this case the relevant ACT Act is Director of Public Prosecutions Act 1990 whereby the DPP and or any member of that office has legal immunity for any acts done in their capacity of acting under the Act provided they have done so in good faith (s.33A).
Try proving the DPP did not act in good faith on the basis that some coppers disagreed about there being sufficent evidence to indict. It would only ever be a matter of opinion unless of course it could be proven the DPP acted maliciously*.
PS - Police and the DPP disagree quite often as to what charge(s) should or should not be preferred on Indictment.
