Promise 'em anything? Up to a point.

State v. Pies, no. 08-2033 (Iowa Ct. App. Sept. 17, 2009)

Pies was under suspicion for a burglary and police found some stolen property in his garbage. Pies agreed to come to the police station for a nice chat. Pies alleges that the inculpatory statements he made were the impermissible products of promises of leniency. During the recorded interview, Pies' confession was induced by improper promises of leniency in exchange for a confession.

The case was reversed and the confession was tossed.

In particular, things that were said included the following:

I am offering you an option to come clean and lessen the charge and work with us on this thing. At this point, if you choose not to cooperate we will take you, I will charge you with the full boat of the crime and you will suffer the consequences.

Folks, the lesson's clear. If a statement results from a promise of help or lenience, it is not voluntary, and is therefore inadmissible. One can, however, say that it is better to tell the truth, but that's about as far as it goes. If the suspect is told what advantages may accrue from a confession, the line has been crossed, because the statements then become promises or assurances.