If ever there was a textbook example of the wisdom of hiring a jury consultant in a criminal case, it was the OJ Simpson trial that just ended in his conviction of all counts.
Jury consultants are expensive and may not make sense in lower stakes cases. But in high stakes cases that involve multiple years of prison time, I believe it may border professional negligence not to have help picking a jury.
This especially holds true when the other side employs a jury consultant.
It is impossible for a single attorney to cover all aspects of a large case. While attorneys have traditionally picked their own juries, if the client has the resources to get help, it may be the single best investment possible in the client's future.
Attorneys should interview several jury consultants before deciding on one.