Argument: Immunity for politicians hurts the image of their office

Far from the worst PR for an office being that a holder of it is on trial, the worst possible public perception of a political institution is that it is wracked with corruption, with it not even theoretically possible to hold its members to account. Prosecuting politicians makes it clear that their office is not a den of impunity, and in the wake of a scandal, restoring public confidence in politicians to come. The public wants their politicians to be accountable and granting immunity harms accountability by denying an option.

Candidate 1: "This is not necessarily true. A politician could be a brilliant diplomat who happens to commit a minor offence such as drink driving; very few indictable offences correlate directly with one’s ability to discharge the mandate of a political office. Historically, politicians have often had their secret vices, including the rumored drug habits of many 19th century politicians, that have not impeded the performance of their duties."
Candidate 2: "The difference between the harm to the office of a politician getting away with a crime and the harm from them being tried for that crime is that the trial is inherently public. Short of widespread corruption – the sort that would probably preclude prosecuting politicians anyway – it is unlikely that unpunished wrongdoing in an office will ever become public. A trial, by contrast, creates a media flashpoint that captures the public consciousness. Thus, even if the damage to the integrity of the office is greater per person in cases of unpunished crimes, the act of punishing the crime informs enough people to outweigh the fact that it may not do as much damage per capita."
Candidate 3: "The concept of retribution is a narrow and dubious foundation for justice. A modern, civilized legal system should not be geared around delivering payback on behalf of victims, but rather around advancing the best consequences for the future. For exactly this reason legal systems give several ways in which defendants can avoid punishment, even though they are technically guilty, if punishing them would have bad consequences; these include jury nullification and suspended sentences."
Candidate 4: "With regard to this issue, elections are unquestionably an effective alternative mechanism. The act of a politician in a liberal democracy holding on to office for another term, by definition, requires public assent. The citizenry has an out: don’t continue electing politicians who aren’t serving the public interest. Regardless, politicians already have a plethora of motives, both legitimate and self-serving, to hold on to public office; this doesn’t move the barometer on incentives to run. Most elections are at least modestly well contested precisely because many qualified candidates really want the position."
Candidate 5: "See argument above regarding other accountability mechanism. Jeopardizing future electoral success, harming one’s political party, and damage to one’s personal legacy are all meaningful checks on the behavior of politicians. To suggest that, in the absence of prosecutions, an under-used tool anyway, politicians will be able to abuse their station with impunity, is simply untrue."

The difference between the harm to the office of a politician getting away with a crime and the harm from them being tried for that crime is that the trial is inherently public. Short of widespread corruption – the sort that would probably preclude prosecuting politicians anyway – it is unlikely that unpunished wrongdoing in an office will ever become public. A trial, by contrast, creates a media flashpoint that captures the public consciousness. Thus, even if the damage to the integrity of the office is greater per person in cases of unpunished crimes, the act of punishing the crime informs enough people to outweigh the fact that it may not do as much damage per capita.
