The grand jury system is one of the chief investigative tools of prosecutors in all State and Federal courts, no longer fulfilling its historic function of protecting citizens against arbitrary or malicious prosecutions. Grand jury proceedings are virtually ex parte and unreviewed. Counsel for witnesses, who may be potential unindicted coconspirators or even defendants, are not permitted to enter the grand jury room, although witnesses are permitted to leave the stand to consult with counsel at any time. Since the grand jury does not generally have its business reviewed, it is not bound by limitations on the subject matter of its inquiry. The scope of admissible evidence is broad. Forms of evidence inadmissible in any other judicial proceeding can suffice to satisfy the government's burden of establishing probable cause that specified defendants have committed crimes. Even the burden of proof, to the extent that there is one, is largely established by the prosecutor, who alone is available to reinterpret for the grand jury the meaning of the probable cause requirement. Generally, unless the prosecutor indicates a willingness to negotiate various alternatives for the client, counsel should indicate to the prosecutor that, if called before the grand jury, the client will invoke the fifth amendment in all matters that might tend to incriminate.