This essay is very long so I'm breaking it up into parts, but it's really meant to be read all together, with each section building on the previous ones.
The wizarding world under the statute: patron and client in the state of emergency
It is only since Order of the Phoenix appeared that it has become clear to everyone that the Wizarding World, for all the wonders it contains, is in fact an extremely lawless place. Until then, the clues had been largely ignored. That Sirius Black could be sentenced to a lifelong torture without a trial was generally put down to a wartime situation, in spite of the awkward truth that the war was in fact already over – not to mention the curious oversight that his case was not once reviewed in twelve whole years of peace, and no one, not even Dumbledore, had any complaints. Moreover, in Harry Potter and the Chamber of Secrets exactly the same thing happened to Hagrid. In spite of the fact that the Ministry of Magic didn't really think he was guilty, they casually put him away in Azkaban for psychological torment, without any sort of hearing and for purely cynical reasons: they felt that they had to be seen to be "doing something" in order to reassure the wizarding public.
In the first four books, however, this sort of injustice didn't affect the protagonists much (except for a foretaste in Goblet of Fire) and so the reader was never fully aware of the degree of lawlessness and misuse of power that wizardkind is subject to. This finally happened with Order of the Phoenix, where a whole string of pernicious laws were more or less introduced on the nod, and the misuse of power and propagation of lies were at last directed at Harry himself.
The reason for this cavalier approach to justice, and for the frightful punishments routinely imposed for almost purely deterrent purposes, is that Wizarding Britain in particular, and the whole Wizarding World in general, has been living under a continuous state of emergency for over three hundred years – ever since the Statute of Wizarding Secrecy was passed in 1692: a state of emergency that has lasted so long that it is taken for granted by everyone. In fact, it seems completely normal; and there's no prospect of ending it, either, because if it ever were relaxed, the Muggles would find out, with unthinkable consequences.
Muggles finding out the secret of what has been really going on – that they have been fed a diet of lies for centuries about the truth of their world, and that they routinely have their memories rearranged by a caste of people completely indifferent to their hopes and fears, their wars and sufferings, would clearly be a catastrophe now. In the long run, in order to prevent the Muggle "Powers That Be" (whether legitimate or criminal) from taking control of their local wizards, adding magic to their arsenals and killing off those that resisted, a wizarding tyranny would have to be established over the Muggle world, ruthlessly wiping out any Muggle authorities strong enough to challenge the wizards. In the meantime there would be every likelihood of genocidal war between various factions of both peoples, fed by panic and revenge – and with hunts for traitors and quislings on both sides. And Muggles are bound to find out in the end, unless the authorities and the population in general are allowed to react quickly and effectively without regard to constitutional niceties.
And they do. Given the need for secrecy, this is a matter of necessity, because in the end enough people will get careless sufficiently often for even the Muggles to work out what's going on, in spite of all the squads of Obliviators, unless wizards as a whole are really terrified of what will happen to them if they do get careless, and unless there's a habit of sorting out problems quickly and only asking questions afterwards, when the evidence has usually been Obliviated. This is the true cause of the seemingly automatic presumption of guilt in wizarding justice – which Harry Potter came up against twice when accused of performing underage magic in front of Muggles: once when Dobby framed him in Chamber of Secrets, and more recently when he had to drive away the Dementors from Privet Drive. "Innocent until proved guilty, Severus" (Dumbledore’s warning to Snape) is the exception more than the rule.
As a result of these constraints, wizarding society has evolved in a very different manner from our own. Since their society can't have a proper rule of law (as we understand it) without risking its own existence, wizards have found another way of ensuring their safety and protection. One way of describing it is what historians call bastard feudalism, whereby in a lawless age (like England in the Wars of the Roses) unprotected men attached themselves to a powerful baron as his retainers: they would serve in his household and fight on his behalf – and he would make it clear to everyone that they were under his protection from enemies on both sides of the law. No enemy could attack a powerful baron's retainers without being punished, and the baron would make sure their lands weren't seized by a neighbour or confiscated by the government, and they couldn't be jailed on a trumped up charge. In return, they would fight for him whenever he needed a private army. In Chamber of Secrets it's hinted and in Goblet of Fire it becomes quite clear that Lucius Malfoy has just such an army, made up of ex-Death Eater commandos. So, it seems, has Albus Dumbledore, as the Ministry of Magic correctly feared – it's called the Order of the Phoenix, and it's made up not of Dumbledore's most powerful friends (like the Wizengamot elders who resigned in his support) but of those who are completely loyal to him. One of the chief developments in Harry Potter's fifth year at school is that he develops a similar armed force of his own. He calls it Dumbledore's Army, it's true, but in fact it's really his own army. Just a small segment of it (Harry's Inner Circle, in fact) turned out to be surprisingly capable of holding its own against a picked force of Voldemort's own elite Death Eaters.
However, a much closer parallel to the way power seems to work in the Wizarding World is the patron-client system, such as existed in Ancient Rome. Indeed, there are several parallels between Wizarding Britain and the Roman Republic: Crouch's sentencing of his son to Azkaban for plotting to bring back Voldemort is a definite echo of the Roman Magistrate Lucius Junius Brutus condemning his own son to death for plotting to bring back the exiled king and tyrant Tarquin; also, the lack of any official representation for Harry at his trial before the Wizengamot follows Roman practice: he was entirely dependent on what he could say in his own defence and the private efforts of an eminent statesman like Dumbledore. Perhaps this is hardly surprising: ease of communication and small population have made wizarding Britain very like an old city state (it even depends on some sort of slave labour) with large portions of the economy in the hands of outsiders (the goblins). Further parallels lie in the gradual decline of the old noble caste (patricians and pure-bloods, both of which were massive casualties of the last round of civil wars, proscriptions and murders) and the way both Rome and wizarding Britain could culturally absorb new blood (freed slaves and Muggle-born) by bringing them up in Roman households and wizarding boarding schools like Hogwarts.
Still, there is one major difference. In Ancient Rome the patron-client system was a formally recognised part of how government and social relations worked. By contrast, the wizarding version is entirely unofficial, and grew up in response to the simultaneous weakness, corruption and capricious power of the Ministry of Magic – the inevitable consequence of that fact that Secrecy always comes before Justice. The Ministry is weak in that it cannot provide protection from abuse of power coming from either side of the law, and its capricious power is all too evident in the draconian punishments it imposes, which usually leave the victim a physical and emotional wreck if not mad, and which most wizards (like Peter Pettigrew) will do nearly anything to avoid.
Basically, the system works by otherwise unprotected wizards attaching themselves to a powerful "patron" and becoming his "clients." The patron will smooth over any problems his client might have with the Ministry of Magic, and use his money and connections to help him out of his difficulties, and keep him out of Azkaban – as Dumbledore did with Mundungus Fletcher. In return, the client himself becomes a part of the patron's entourage and connections. The patron ends up with a large body of wizards dependent on him whom he can rely on (a private army, in other words) which effectively puts him above the law, because the wizarding world doesn't actually have armies, at least in the Muggle sense of the word. Some patrons may well have an even more powerful patron of their own, and a wizard at the top of a patronage tree is a very powerful figure indeed: such are Dumbledore, and Lucius Malfoy, to whom wizards like Crabbe and Goyle defer. Their sons in turn attend on Draco, as bodyguard and entourage; this makes them part of the same patronage network, because Draco's patron is his father.
The strength of a particular patronage network depends not only on the patron and clients themselves, but on the strategic resources which they control, and over which the struggle for power is fought. As A.J. Hall explained in her recent paper "Justice in the Wizarding World":
"There exist a number of key strategic pieces over which each primary [patronage] network seeks control or influence, Hogwarts and the Ministry being two, and Harry himself representing a third (others may be Gringotts, The Daily Prophet and possibly St Mungo’s). A network not controlling a particular strategic piece has the options either of outright conflict for possession of it, entering into an alliance with the network that does have control of the strategic piece, or working to discredit or eliminate the importance of the piece concerned."
This is precisely what Fudge's network attempted to do to Harry Potter once they had turned against Dumbledore. Harry was in Dumbledore's pocket, so Fudge's faction in response did all they could to discredit Harry, and so eliminate his importance.
Continued in Part 2...