This section is from the book "The Law Of Contracts", by William Herbert Page. Also available from Amazon: Commercial Contracts: A Practical Guide to Deals, Contracts, Agreements and Promises.
The cases in which it now is material whether a judgment is a contract or not are generally cases involving the impairment of the obligation of contracts, the period of limitations, the rule as to necessary parties to actions, and other questions arising where the legislature has made different provisions for actions on contract from those for actions generally.
While there are some decisions to the contrary1 the weight of authority, supported by decisions of the Supreme Court of the United States, is that a judgment is not a contract within the meaning of the clause in the United States' Constitution preventing a state from impairing the obligation of contracts. Hence the legislature may interfere with the collection of a judgment based on tort by forbidding the sale of property for an act done during the Civil War,2 or by reducing the tax rate in the municipality so that the judgment cannot be collected,3 or by changing the rate of interest which the judgment bears, accruing after the passage of the act.4 But in some cases a statute changing the rate of interest on judgments is held inapplicable to judgments previously rendered.5 There is, therefore, a decided conflict of authority on this point. As an additional complication some courts have tried to distinguish cases where the contract provides what rate a judgment rendered thereon shall bear6 from all other cases, holding that in such cases a change in the rate of interest of judgments previously rendered would impair the obligation of contracts, but not in other cases. A subsequent statute as to fish-ways may affect a judgment authorizing a dam to be built across a creek, subject to such conditions as the court should impose concerning the obstruction of the passage of fish.7
2 Hilton v. Guyot, 159 U. S. 113 (201).
3 Chase v. Curtis, 113 U. S. 452. Thus under a statute making stockholders liable only on contracts entered into by the corporation while they were stockholders, a judgment rendered on a cause of action was held not to be a contract so as to bind a stockholder who bought stock after the cause of action accrued, but before judgment. Larrabee v. Baldwin, 35 Cal. 155. Reed v. El-dredge, 27 Cal. 346, is really not in point. It holds that a judgment rendered before the passage of the legal tender act was not a contract for the payment of a debt in gold or silver; hence the court in a suit on such judgment after the passage of such act could not render judgment for the payment of the debt in gold or silver.
1 Skinner v. Holt, 9 S. D. 427; 62 Am. St. Rep. 878; 69 N. W. 595 (change in exemption laws).
2Freeland v. Williams, 131 U.S. 405.
3 Louisiana v. New Orleans, 109 U. S. 285; State v. New Orleans, 38 La. Ann. 119; 58 Am. Rep. 168.