I read in this article that a woman is suing Southwest airlines for $10 million because she was forced to wear a mask.
This sounds absurd to me. Can someone just arbitrarily demand millions of dollars? If not, how do lawsuits work?
Can you just sue anyone for anything?
But being able to sue falls nowhere near being able to win.
To sue literally means to deliver properly formatted papers to the court, pay the fees, and deliver copies to the other party. Bingo! You are already suing!
Then what? That's the real question.
Since you didn’t mention the country: In Germany, you can sue anyone for a large amount if you wish to. However, the court will set court fees and lawyer fees as a percentage of the amount that is in dispute (here: $10 million, court fees and lawyer fees will be in the ten thousands).
The loser pays. But should you actually win $10,000 (unlikely), you lost 99.9% because you asked for $10 million, so you have to pay 99.9% of all the fees. So this is a very bad and costly plan.
Yes, it is true that in the US, anybody can sue anybody for anything.
However, it is worth noting that there are also recourses when cases are filed without any merit. For example, a defendant can countersue for frivolous lawsuit or abuse of process if a lawsuit is simply ridiculous or pure harassment. It is also possible that the lawyer could face penalties from the bar association (potentially up to and including disbarment).
Furthermore, many US jurisdictions have laws regarding vexatious litigation. For example, in California, someone who chronically files frivolous legal actions can be added to a list of vexatious litigants, in which case they are barred from filing any further actions without permission from a judge.