A City Guide To Ranghulu for laissez-faire: a French phrase used to characterize economic systems with little to no government intervention in private sector markets. Laissez-faire is consistent with the concept of free enterprise. law of demand: an observed negative relationship between the price of a good and the number of units purchased of that good. This law is used to explain why demand curves have a negative slope. law of diminishing marginal returns: the understanding that, at some point, an individual or firm will obtain smaller increases in benefit from each additional unit consumed or produced. law of supply: an observed positive relationship between the price of a good and the number of units purchased of that good. This law is used to explain why supply curves have a positive slope. A City Guide To Ranghulu 2016.