It’s part of a now-familiar pattern. A gunman goes on a shooting rampage at a school, college, theater or mall. The victims’ families grieve, the politicians debate gun laws, and often within weeks or a few months, the first civil lawsuits are filed.

Sometimes the defendants are relatives of the shooter. Sometimes they are makers of video games. Sometimes they are gun manufacturers. But over the past 15 or so years, one thing seems clear: It’s fairly difficult for plaintiffs — the victim’s families — to win large verdicts or collect substantial settlements.