I’m trying to find out if there’s a correlation between win rates in civil cases and the wealth of the parties involved. I’ve searched google scholar but the only thing I can find is a paper regarding who wins patent disputes. I suspect my lack of knowledge regarding legal terms is why I can’t find this research, hence why I’m asking for help here. Does anyone either know of any research papers regarding the impact of wealth when it comes to winning court cases. I’m mostly interested in civil cases, but any research papers on the subject would be appreciated :)
It is difficult to quantify in a useful way.
Part of the issue is that calling the courts "dispute resolution forums" is misleading. Courts are "rights enforcement forums." They are designed to provide remedies to people whose rights have been violated, not to neutrally resolve disputes between parties. And, most lawsuits are mostly one sided, not circumstances where both sides have legitimate grievances for which they seek redress.
The vast majority of cases brought in courts, by raw number, are debt collection actions, evictions, and foreclosures. These cases are overwhelmingly brought by landlords against tenants and by lenders (mostly banks and big businesses that extend credit) against borrowers. I'll note those in bold.
For example, in Colorado, in 2010, there were 116,346 civil cases filed in District Court in Colorado (the state trial court of general jurisdiction). Summary mortgage foreclosure actions accounted for 39,404 of those cases. State tax lien filings accounted for another 45,528 filings. These case make up 73% of the district court civil docket. There were 30,236 cases of other types on the District Court civil docket in the state. About 5,809 are claims that fit in the heartland of tort law: cases involving personal injuries including worker's compensation cases that end up in court) and wrongful deaths, breach of warranty, public nuisance, sexual harassment cases, fraud cases and malpractice cases (of all kinds) as well as motions to approve transfers of structured settlements. About 3,527 involve judicial efforts to establish title to or possession of specific pieces of property often in connection with the collection of a debt. A big portion of the remainder of the cases, 13,165 involve contractual disputes or rights in real estate or other property (a fair share of which are basically debt collection cases such as mechanic's lien foreclosures and large dollar non-payment of contractual debts that aren't seriously disputed). There were 722 appeals from municipal or county courts and 72 cases to confirm arbitration awards. There were 5 public utility cases, 236 cases reviewing acts by local governments and by government officials, and 31 special district cases, 470 declaratory judgment cases, 583 injunctive relief cases, 1,484 cases classified simply as "other", 29 restraining order cases, and 334 contempt of court cases. These courts also handle divorces, child custody cases, paternity cases, probate cases, felony cases, and post-trial collateral attacks on criminal convictions.
County courts in Colorado (at the time state courts with a $15,000 jurisdictional limit) had 148,425 debt collection money claims, 42,689 eviction cases, 531 cases to repossess personal property, 13,257 restraining order cases, 1,496 name change petitions, 27 purely administrative registrations of foreign judgments, and 529 cases classified as "other." These courts also handle misdemeanors and traffic violation cases. About 93% of civil cases in county courts in Colorado are debt collection and eviction cases.
Overwhelmingly, the landlords and money lenders win these laws and are more wealthy than the tenants and borrowers who overwhelmingly lose these lawsuits. A very larger share of the time these cases are lost by default. In very large share of the cases in which there is a default, it is because there is no viable defense: the promissory note or credit card was not paid as agreed, usually because the debtor was unable to pay it. In eviction cases, usually, the rent was not paid on time, often for the same reason. When there is not a default, there is usually a settlement or payment plan. We focus on the very rare cases that go to trial, but those are edge cases.
There are good studies that show that defendants in debt collection and eviction lawsuits secure better results for themselves when they are represented by counsel, which they usually aren't, than when they are not. But defendants in debt collection and eviction lawsuits who are represented by counsel still usually lose anyway, just on somewhat less harsh terms. So, to do any nuanced analysis of the role played by affluence and wealth in litigation, you need to start by having a fairly sophisticated sense of what is and is not a win, and this is far from obvious.
In contrast, tort lawsuits for personal injury are usually brought by ordinary individuals from all walks of life who get injured due to bad luck against either other ordinary individuals backed by the resources of an insurance company to defend and settle their cases, or against property owners, or against businesses. There is typically not an affluence divide in these cases, or if there is, the injured person is less affluent, and the injured person usually secured money from the person who they claim caused the injury, either at trial, or far more often, in settlement reached in the shadow of what would have happened if they case went to trial. Lawyers rarely commence personal injury lawsuits were there isn't a good argument that their client should win.
Personal injury tort cases make up a thin sliver of cases filed and judgments entered relative to debt collection and evictions lawsuits. These cases make up about 2-3% of the total court system docket (but account for about 75% of civil jury trials).
There is litigation other than debt collection, eviction and personal injury litigation. But in some of those kinds of cases, like probates and divorces and bankruptcies, where determining who is the winner and who is not is even more challenging. Indeed, in many such cases that are actively litigated, everyone ends up losing and no one ends up winning.
In the law and economics literature, the classic study (Leeson 2011) looked at who won disputed land title disputed in medieval England in the days of trial by combat. It turns out that back then, the wealthier party, who could afford to hire better champions in a trial by combat, usually won.
The question asked feels like it is trying to build on that model and determine if that kind of law and economics finding can be applied to modern day litigation with the controlling factor being who hires the best lawyers to go to trial for them, rather than who hires the best champion in trials by combat. Many cynical people think that this is how the legal system works now.
But overwhelmingly, at the threshold of who gets any relief relative to the status quo from a court in litigation, the answer is almost always the person who brings the lawsuit, 95%+ of the time, either in a settlement, or at trial, and whether the person bringing the lawsuit is usually more affluent or less affluent than the defendant is dominantly a function of what basis for the lawsuit, while whether the parties have lawyers, and if so, how good they are, are only second or third order considerations.
None of this is to say that hiring good lawyers, who, on average, are more expensive than mediocre lawyers, doesn't improve one's outcomes at the margins, or that affluent people are more able and willing, on average, to hire good lawyers than less affluent people. But, to see the difference, you need to think about relative degrees of winning or losing, and you need to recognize that the nature of the lawsuit matters.
Along the same lines, studies comparing people who have private criminal defense counsel (because they can afford to do so) with people who have public defenders (who are by definition indigent defendants), usually show that the outcomes at the guilt-innocence phase are very similar between the two, although public defendants pay much less attention to their clients and provide much less "customer service". The divide in those cases is not mostly on guilt-innocence outcomes, but in the ability of affluent defendants with expensive criminal defense lawyers to have more satisfying lawyer-client relationships and experiences, and to take better advantage of alternative sentencing options, rather than just getting thrown in jail or prison.
To some extent, this is a long winded way of saying that the research you are looking for, in the plainest terms as stated in the question, doesn't really exist. This is, in part, because in many contexts at a shallow level, it is obvious, and in part, because, viewed more deeply, it is extremely subtle and requires very rich data to discern which makes it hard to gather and hard to compare.
The most on-point article I know of is Albert Yoon's The Importance of Litigant Wealth:
While proponents of tort reform have argued that the current legal system makes wealthy individuals vulnerable to frivolous lawsuits, this Article makes the opposite argument: the current system actually disfavors those with resource constraints. In litigation, prospective plaintiffs with resource constraints may elect not to bring suit. Plaintiffs who do bring suit may find that that wealthier defendants can exploit their resource advantage through various mechanisms -- such as prolonged discovery -- to prevail or resolve the dispute on favorable terms. Wealthier plaintiffs can use their resource advantage to achieve similarly favorable terms.
It may direct you to other helpful resources, as well.