Generally speaking, a downward departure happens by motion of one of the two parties in a federal case. The basic argument would be that the recommended guideline range for the offense is not reflective of the severity of the offense (too much punishment for the crime) or at least the defendant's role in that crime (happens a lot in conspiracies). The problem is that sentencing courts generally cannot depart below the recommended guideline range unless, for instance, the defendant is receiving safety valve protection b/c he or she has no significant criminal history or the defendant is receiving a 5k adjustment for assisting the government. You would know if the defendant was getting one of these departures.
Beyond these, federal judges are usually going to tell you, "I wish I could go below this mandatory minimum, but the law does not allow me to do so." You're probably best off trying to argue that, for one reason or another, the mandatory minimum does not apply to this defendant, so right now what he or you need to be looking for is a sharp attorney well versed in the sentencing guidelines.
It may not work at all. A downward departure does not allow the judge to go below the mandatory minimum sentence. The only way the judge can go below the mandatory minimum sentence (even if the judge wanted to) would be for the defendant to either qualify for "saftey valve" or for the AUSA to file a 3553(e) motion. Unless one of he hose two findings are made by the Court, the judge may not, by law, sentence to anything lower than the mandatory minimum.
This would best be explained by this individual's Federal Defender or retained defesne attorney--although it's difficult to downwardly depart from a "mandatory" minimum. It's possible to downwardly depart to the minimum. So many variables involved, your question is impossible to answer.
In the Seventh Circuit, where I do most of my federal court practice, the concept of "departure" has little meaning left now that the sentencing guidelines are advisory rather than mandatory, and sentencing is imposed pursuant to Section 3553. I gather from the responses I have seen over the years from my colleagues that departures continue to play a more significant sentencing role in other circuits.
In general, a prosecutor can file a motion for a sentencing reduction for a cooperating defendant, and can recommend a sentence below the advisory guidelines and/or below a mandatory minimum. When a mandatory minimum is at issue, other attorneys have correctly advised that a competent defense attorney will seek an agreement for a reduction under both statute and guidelines, so as to give the court authority to sentence below both statutory minimums and advisory guidelines. The ultimate sentence will then be determined by the court, with prosecutors advising the court of efforts at cooperation, and possibly also recommending a specific term or reduction. The defense will also be able to argue for a reduction, along with supporting arguments and evidence about cooperation, mitigation, and other factors that favor leniency. Anyone facing a federal prosecution should obviously work closely with retained or appointed counsel to understand any agreement in a specific case, and to understand any sentencing options based on cooperation. General information in a public discussion forum is no substitute for working closely with a lawyer on a specific federal case to understand all proceedings and defense strategies.
The author provides answers on this site based on hypothetical questions and fact patterns. The answers provided are for general educational and informational purposes only, and they do not constitute legal advice, which would require a personal consultation and representation agreement. Questions and answers on this site do not create an attorney-client relationship, and the communications are not privileged. Any citizen with a legal issue should consult personally with an attorney and should rely only on legal advice provided in a formal attorney-client relationship.