Assuming the laws in your state have no special quirks...
1) You have no obligation to go. Nor do you have the right to show up, except to watch the proceedings as a member of the public. Your roommates can call on you as a witness but you can't insert yourself into the action without their say so.
2) You are not a 'party' to this action, as I said above. You can go ahead and help your roommates with cash or whatever, but you are not obliged to, unless you insist on producing a written contract and signing it with your roommates.
3) No receipts = no evidence. Pretty tough to prove your story even though oral testimony is not excluded. But you don't need monthly receipts. If you paid this guy sometimes via check, you probably have a few months' worth of payments on your bank statements.
4) Usually your roommates (whoever's got his name on the list) will be held liable. Most cases like this are straightfoward. Whoever who shows up will often get hit with the full amount claimed, unless he can convince the judge otherwise. If nobody shows up, judgment to plaintiff, then they'll try to look for somebody's workplace and serve him some garnishes and whipped potato. AKA Sheriff shows up and talks to his boss with a court order.
5) To physically evict you guys will require yet another court order. Landlord is never allowed to show up with some thugs and throw you into the street. Until the Baliff actually comes with a piece of paper, landlord is not permitted to enter your place or lock you out or do anything unfriendly like turning off the heating.
LASTLY:
The law assumes that when you form a rooming relationship with other people and put your names on the lease, you know or trust each other. It's ridiculous to expect the landlord, a company or an absentee owner or some elderly pensioner trying to make some money from his property, to know which ones of you guys has been trusted with money and who absconded with money.
If you guys didn't make sure that the guy whom you paid actually paid the landlord, too bad. He can abscond and there's not much you can do about it, except tracking him down in another state and suing him. Sure, his name may be mentioned in a judgment in this jurisdiction against him, but it's not important unless he eventually applies for a legal job, law enforcement job or banking job (the background checks are very strict for these occupations).
BTW which jurisdiction are you in? State X, County Y? Whenever you want to ask people for advice, at least give better information. Asking any legal aid bureau will entail giving these details, so that people can advise you based on the laws applicable to you.
OH, and what I say must not be construed as legal advice. It's just BS I cooked up
for the entertainment of geekhackers. We have no relationship and no money has passed between the two of us
