How can a person with a similar experience with the defendant, help the plaintiff in a lawsuit?
You may bring Joe as witness or present some sworn testimony from him. That could be in the form of affidavit, deposition transcript, or by testifying in court.
In what way can I use Joe's story?
Joe's testimony will be relevant to the extent that it proves the defendant's pattern of conduct or system for doing a thing. Many (if not all) jurisdictions in the U.S. had a provision similar to Michigan Rule of Evidence 404(b)(1):
Evidence of other crimes, wrongs, or acts [...] may, however, be
admissible for other purposes, such as proof of motive, opportunity,
intent, preparation, scheme, plan, or system in doing an act [...]
when the same is material, whether [they] are contemporaneous, or
prior or subsequent to the conduct at issue in the case.
Thus, Joe's testimony would not prove your entire claim, but it can discredit important aspects of defendant's foreseeable denials in your matter.
In some way the suggestion in the other answer makes sense, but I would discourage you from bringing suit together with Joe. That is because, despite all similarities, your claim are Joe's claim are different instances:
- Each cause of action stemmed from a separate contract;
- each contract/cause involves a different plaintiff;
- the statute of limitations of each wrong started running at different
- and your history with the defendant might differ from Joe's history
with him on relevant aspects in a way that could prejudice you.
Furthermore, if the defendant requests that the suits be separated, you and Joe would have no persuasive arguments on why your matters should remain consolidated.
Lastly, the mere fact that a complaint is filed by two or more plaintiffs will not prompt a judge to act with honesty or with competence.