Is an argument used by certain of David Icke's fans and similar cranks to, allegedly, get out of all taxes, fines, being arrested, or suchlike. It's sold at seminars and circulated on crankier web fora and Youtube comments and, during the Occupy protests, by people in them who wrote for the Guardian's Comment Is Free section, which is a judgement both on the Occupy movement (but do you really expect better from Bollinger Bolsheviks?) and on the Guardian, especially considering the latter is also the home of Ben Goldacre and various other skeptical types.
It goes something like this. Basically, all law, other than the common law (which Freemen interpret as Magna Carta and case law) is contractual in nature, and statutes only apply to you if you agree with them or consent to their being in force. Furthermore, they only then have an effect on your legal person, and not on you yourself, by which they mean your birth certificate. Therefore, you can escape all this by not being your legal person and becoming a freeman on the land in "lawful rebellion" and suchlike. You do this by not using the names printed on official documentation to refer to yourself, which creates something called "joinder" and puts you under the ambit of statute law. Instead, if this documentation states you're John Smith, you claim to be JOHN SMITH, or John of the family Smith, or John: Smith, or commonly-known-as-John. Apparently all names on birth certificates are Crown Copyright and as such property of the Government, so when Romeo doffs his name, he also escapes the authority of statute law.
Therefore, you aren't the person against whom this tax bill / debt / County Court Judgement / TV licence fee (the anti TV licence movement is awash with these people, when if you object to the TV licence fee it's far easier just to avoid it by throwing out your telly and watching stuff on iPlayer/4od/etc. at a time other than the programme is broadcast) refers.
No, really, people actually try this. And it gets weirder.
They then allege that by stepping outside The System, they can escape things, and rules don't apply to them. They claim that all Judges are in breach of their oaths to the Crown as they are bound by statute law which they claim has no legitimacy as a result of the above. This results in such hilarity as asking the Judge to show their original oath of office. Another freeman amusement is, in the US, objecting to the Court having a gold-fringed US flag in it as this makes it an admiralty Court and thus leads to hilarity as shouting "man overboard!" when the Judge rises afterwards and the freeman attempting to take control. Or, because they're their own person and have this inalienable rights that they claim, whenever a Police officer, traffic warden, whatever, attempts to talk to them about anything, they then give a "fee schedule" saying that they will consent to being arrested, fined, and suchlike, but subject to a list of charges for so doing which they claim are owing by the person.
For the record, yes, it is woo, and abject woo at that. The Courts are well aware that people will attempt to use pseudonyms, aliases, and similar in their dealings, which is what freemanism is, really, just dressed up in gratuitous latin and legal-sounding nonsense. And there are ways around it. It is perfectly acceptable to put "aka" by a party's name in Court proceedings or similar when they have known aliases. It is also possible to show evidence that "John: Smith" is, in fact, an alias of John Smith. And that's before we get back to the widespread case law that if a person uses multiple spellings of their name it doesn't necessarily make them a different person. Not only that, but the idea that statute law is contract based is clearly nonsense, especially given the Freeman hard on for the Magna Carta, only a handful of sections of which are in force today, and which within a century was superseded itself. The law is the law not because of arcane verbiage or pomp and circumstance, but because those tasked with enforcing and keeping it recognise it as same. So unless a critical mass of all emanations of the executive and judiciary were to agree that all statutes are unenforceable without some sort of contract, freemanism cannot work regardless of how elegantly argued it is. This is why forcing through change and law reform via the Courts is such a difficult process; it's easy enough to get a first-instance Judge to agree with your novel legal point but it's no precedent unless it gets to a higher Court on appeal. And even if the Court of Appeal gave credence to freemanism, no doubt legislation would be introduced, and very quickly indeed, to shut that party down.
The worst thing about it, though, is that there are increasing numbers of people who believe it. They spend their money to respond to spam-advertised e-books that usually target people worried about debt and their finances and similar, who are sold freemanism as a sure-fire get out of debt free card. They then find that it is not such a silver bullet, and that using it gets you bawled out by a Judge, and realise, often belatedly, that they've been sold a bill of goods. Those who promote freemanism, when asked about this, then either hide behind "you're doing it wrong" or advocate covering it up with yet more freemanism bollox. I have seen one report where a Judge ended up asking where the freeman got this stuff (here), and also where a Judge explicitly rejected all of it (here) and held the person attempting it in contempt. These people who push it must know freemanism has failed every time it has been employed other than to blag an adjournment by dint of the maxim that bullshit baffles brains yet still sell it to people as a viable thing. This is deeply irresponsible and shameful, in my experience; it's preying on the desperate in the same way as homeopathy and Gillian McKeith.
Speaking of which, freeman types like to film hearings and post them on Youtube upon where the cesspit that is the comments section can martyr them and/or as further "evidence" that all legal types, lawyers, solicitors, barristers, the entirety of the judiciary, etc., are conspiring to keep them from THE TRUTH about freemanism so they can make lots of money out of your ignorance. As opposed to those characters who flog dodgy ebooks in order to make lots of money out of your ignorance, of course. But the law does not work that way. As I have said, it is the law because there is a general consensus amongst those involved in its operation that it is the law. Recursive? Yes, but it works in practice.
I think I've said enough. However I will leave you with one tale I heard from a barrister I met at Bow County Court while shooting the shit in between hearings. The previous week he had been representing HM Revenue & Customs against a self employed chappie for arrears of income tax. Chappie lodges a 250 page defence and counterclaim based on freemanism. He was saying that because he was really Bob: of the family Glover not not Robert Glover he didn't have to pay income tax as he had not consented to paying it. He also had sent the Revenue that fee schedule for dealing with him and claiming thousands and thousands of pounds for that, for being wilfully denied his rights as a free person under Magna Carta (the only right extended to all free persons by which is, of course, habeas corpus; the whole rebellion and seizing Crown lands was aimed at the nobles who browbeat King John into signing up to it, not ordinary schleppers like you) and suchlike. Anyhow, chappie starts presenting all this but then a few sentences in to what was no doubt a lengthy and incoherent ramble, the Judge sees a way out. "Have you paid the Court fee for lodging this counterclaim?" he asks.
"No," says chappie. Because in the freeman universe, if you pay the Court fee, you're contracting with the Court, joinder is established, and the universe probably ends.
"Then I'm afraid it wasn't properly filed, and I can't consider it," says the Judge, before theatrically dropping it into the bin in the corner of the Courtroom.
I doubt this one found its way onto Youtube somehow.