Law Professor Mark E. Steiner, in the February 2009 issue of the American Bar Association Journal, has investigated this question with the help of The Papers of Abraham Lincoln Project, which maintains a database on Lincoln’s law practice that contains 5,173 cases involving him and his partners.
Professor Steiner found out the following:
“Common-law cases made up roughly two-thirds of Lincoln’s circuit court practice. The largest two categories of these cases were assumpsit (1,240 cases) and debt (667 cases).”
[Assumpsit is an action for the recovery of damages by reason of the breach or non-performance of a simple contract, either express or implied, and whether made orally or in writing. In the United States, assumpsit became obsolete in the federal courts after the adoption of the Federal Rules of Civil Procedure in 1938. Most if not all states have moved to similar rules, but some states continue to recognize assumpsit as a common law or statutory cause of action.]
“Chancery made up about a quarter of Lincoln’s docket in the circuit courts. There, he handled such equity matters as petitions to foreclose mortgages (more than 200 cases), to partition real estate (142 cases) or to sell real estate to pay debts (75 cases). He was a lawyer in 145 divorce cases and 44 dower petitions.”
[For most of the history of modern law, there were two "sets" of courts: the courts of law and of equity. Chancery, or equity cases differ from “common law” cases. The focus is on getting "equitable relief" when there is none available “at law.” There is no jury. Remedies available at common law in Lincoln’s time were generally limited to simple orders to pay certain sums of money or determinations by the court of who owned what assets. Chancery cases emphasize fairness and flexibility and allow special remedies (such as injunctions or partition of real estate) other than simple orders to pay certain sums of money. Today, most U.S. courts have merged law and equity.]
Lincoln handled relatively few criminal cases – only 27 of them.
“The majority of Lincoln’s cases involved debt. Of the 5,173 cases in the Lincoln law practice database, 3,170 are indexed under “debtor and creditor.” He represented creditors more often because debtors routinely failed to appear.”
“While Lincoln is sometimes thought of as a “railroad lawyer,” that work actually was a small part of his docket, and primarily during the 1850s as railroads began to spread across the United States. (As president, he signed the law that made construction of the first trans continental railroad possible.) He handled 133 cases involving railroads, representing various lines 71 times and opposing them 62 times.”
“Lincoln and his partners handled more than 400 appeals before the Illinois Supreme Court; in roughly half, they were hired specifically for the appeal. Lincoln also was involved in at least 340 cases in the federal district and circuit courts.”
You can read the entire article here.
See also the page of resources on “Lincoln and the Law” at the Library of Congress, here.