Dean Martin's final lead role has somehow managed to slip under the radar of his fans and 70s crime thriller aficionados. Watching this, I expected to find some critical flaw that accounts for it, but found none. Maybe playing against genre expectations hurt the reception. To me that is not a flaw.
Like others have said, this is a very 70s movie. This time the renegade is not a cop but a defense lawyer. Cop is not the law, he's there to enforce it, is the running theme. There are delightful gags involving Ricco's dog that could be from Columbo, and Dino makes fun of his own golf playing. Cindy Williams plays a spunky aid that Ricco tries to help find a man. Philip Michael Thomas of Miami Vice fame has a memorable early performance.
Inspite of the mellow insider group, pay attention to the case. The action is on the streets. Not much happens inside a courtroom. You may think you are about to see an open and shut case, but there are twists and turns. There are clues as well. To avoid spoilers, avoid Robert Ebert's review that misses the point.