What do we need to do in order to qualify as a plaintiff?
For a viable lawsuit? You need to show either A), that you have suffered a quantifiable injury (a loss of some sort), or B), that the regulation has had a provable "chilling effect."
In other words, if you sue because your feelings are hurt, you will lose. If _I_ sue, I will lose because I'm not affected by the blue card scheme.
If you sue because of the lost time and money, you have standing (you have suffered injury), which opens the window of opportunity for a tactic which is expensive, but very effective. You can sue the county for this minor injury, and probably lose. Then you can sue them AGAIN after losing, over and over, one suit for each firearm which you have registered under the blue-card scheme (three pistols, three separate injuries, three separate lawsuits).
When you run out, someone else takes over. Or maybe you get a dozen people to sue, all on the same day.
You have to get the government's permission to sue (or, more precisely, you have to get the government to refuse any other suitable correction). This means that your first stop is the City or County Attorney. You present your grievance and demand for recompense, in this case for the time that you spent (at your normal wage) and the costs of going to get the firearm registered. Take your grievances IN WRITING, IN PERSON, one at a time (and don't gather in one place beforehand). Your demand will be either ignored or refused -- get this IN WRITING -- at which time you are able to file suit.
Every case must be heard, even if summarily dismissed, and there are only so many courtrooms and judges. BTW, if you do this, DO NOT accept "commissioners," pro-tems or anything other than a full, elected judge to hear the case. A judge pro-tempore can be appointed or a warm body commissioned as fast as they make deputies in John Wayne movies ("Hold up your hand and say 'I do!'") -- but they have to ask whether you accept them or not, so DON'T.
The filing fee won't cover the costs of the resources that they will be required to provide, and if enough of you play this game, they won't have the resources necessary to hear each case within a reasonable time (they may put them together as a class, or the judge may assembly-line the cases ("John Smith? Your case is without basis and therefore summarily dismissed. Jane Doe? Your case is without basis and therefore summarily dismissed . . ."). This is the argument AGAINST everyone filing on the same day, because they will be heard on the same day. If you file on separate days, you get separate court dates -- when the county figures out what's going on, they will try to bring them all together on the same date, but you can refuse to accept those changes. However, if you do all go in, you can request changes of court dates as well, to spread out the hearings.
The objective is to make it too much trouble to deal with you, enough so that the clear solution is to remove (or allow vacation of) the regulation. This is such an effective tactic that variations have been used a number of times.
This, BTW, is how Jesse Jackson became a multi-millionaire. He got his rent-a-mob to go into banks and other businesses to make small transactions while demanding extra service (such as taking in jars of pennies to make payment, opening accounts then immediately closing them, sending in hundreds of people to get change for one dollar each, etc). The banks and businesses would spend the whole day making no money, with their regular customers being unable to get their own business done -- the next day, Jackson would offer them a chance to end the trouble, and part of the solution was the businesses "donating" to Jackson's "civic organization."
The bottom line is that if the regulation offers little (or no) advantage to the people with authority to void it, just make it too expensive to keep and they will get rid of it.
