Within the framework of short, satisfying detective plots featuring his recurring character "Inspector Maigret," Georges Simenon maintains a steady flow of observations about class, sex roles, economic tensions, and everyday etiquette in mid-20th Century France. In ambition and quality, the project recalls the human comedy of Balzac (who Simenon admired), spread over years of genre installments. Simenon also wrote "real" literature during this period -- stellar books such as Monsieur Hire's Engagement and The Man Who Watched Trains Go By -- but taken as single project, and given changing ideas of the relative value of "genre" within the literary fraternity, the Maigret books are real enough.
The novels don't follow a strict chronology; however, by the time of Maigret and the Lazy Burglar (1961), our intrepid Parisian police functionary is nearing retirement. Simenon meditates on the aging of his character and the changing nature of police work since the series began thirty years before. In the early stories Maigret could run an investigation as he desired, whether it meant wandering the streets waiting for intuitive connections to present themselves, or hauling in suspects and (non-violently) sweating confessions out of them.
By the 1960s, police departments had begun shifting case management and decisionmaking away from inspectors and more towards prosecutors' offices, within a modern, scientific system of justice that (in Maigret's opinion) elevated "exams" and "efficiency" over street knowledge. Meanwhile, the rights of the accused received more recognition than they had in the 1930s -- perhaps in imitation of the American system? Maigret doesn't tell us. Even though he rarely if ever abused his earlier powers, by the time of Lazy Burglar, he resents having the discretion taken away, and especially having to cede it to remote bureaucrats who lack his judgment and life experience. (This is less Dirty Harry than it sounds.)
In Lazy Burglar [caution: plot points], Maigret covertly rebels against prosecutors by pursuing his own investigation of a case, and then rebels again when his digging "solves" the crime. He simply declines to bring the truth to his superiors, reasoning that because the murder victim, a burglar whose professionalism Maigret somewhat admires, is a marginal figure (reminiscent of Monsieur Hire) and the likely murderer a sheltered aristocrat, justice will not be served in any event. Ultimately Maigret retains the Godlike power not to prosecute, which, as the reader well knows, he exercised many times in the course of a long career. Despite the crook's getting away with it, the story has a happy ending, which will not be revealed.