The expression qui tam is, in fact, an abbreviated form of a maxim of Roman law, expressed in Latin, qui tam pro domino rege quam pro sic ipso in hoc parte sequitur: who as well for the king as for himself sues in this matter.
Also known as informer or bounty statutes.
As defined in John Bouvier's law dictionary:
"When a statute imposes a penalty, for the doing or not doing an act, and gives that penalty in part to whosoever will sue for the same, and the other part to the commonwealth, or some charitable, literary, or other institution, and makes it recoverable by action, such actions are called qui tam actions, the plaintiff describing himself as suing as well for the commonwealth, for example, as for himself."
An example of the application of the principle of qui tam in statute is the Civil False Claims Act of the United States (Chapter 31 of the United States Code) which rewards and enables private citizens to litigate in the name of the U.S. Government against persons they suspect are committing fraud against the government, and then, if the litigation is successful, share fines or other monies recovered with the government.
In Vermont Agency, Justice Scalia of the US Supreme Court offers an excellent history of qui tam statutes in England and in the United States, and describes the present Federal statute as follows:
"Originally enacted in 1863, the False Claims Act (FCA) is the most frequently used of a handful of extant laws creating a form of civil action known as qui tam. [T]he FCA imposes civil liability upon 'any person' who, inter alia, 'knowingly presents, or causes to be presented, to an officer or employee of the United States Government . . . a false or fraudulent claim for payment or approval.'
"The defendant is liable for up to treble damages and a civil penalty of up to $10,000 per claim.
"An FCA action may be commenced in one of two ways. First, the Government itself may bring a civil action against the alleged false claimant. Second, as is relevant here, a private person (the relator) may bring a qui tam civil action "for the person and for the United States Government" against the alleged false claimant, "in the name of the Government."
"If a relator initiates the FCA action, he must deliver a copy of the complaint, and any supporting evidence, to the Government which then has 60 days to intervene in the action. If it does so, it assumes primary responsibility for prosecuting the action, though the relator may continue to participate in the litigation and is entitled to a hearing before voluntary dismissal and to a court determination of reasonableness before settlement. If the Government declines to intervene within the 60-day period, the relator has the exclusive right to conduct the action and the Government may subsequently intervene only on a showing of good cause.
"The relator receives a share of any proceeds from the action generally ranging from 15% to 25% if the Government intervenes (depending upon the relator's contribution to the prosecution), and from 25% to 30% if it does not (depending upon the court's assessment of what is reasonable) plus attorney's fees and costs."
- Vermont Agency of Natural Resources v. United States ex rel. Stevens, 529 US 765 (2000)