The ability of government to perform its necessary public health, safety, and welfare functions would be seriously hampered. Suppose, for example, that instead of an arterial highway, the project is a high-voltage transmission line. Or suppose that the new project is a noisy factory. It seems clear that if any legislation to compensate for partial takings were to be passed by Congress, a very scary precedent would have been established. The government, for example, frequently changes interest rates, which directly affects the value of public and private securities.
Landowners have no constitutionally guaranteed right to upzonings.
In the earlier highway example, property near an improved intersection may be upzoned to commercial uses. It merely suggests that compensation for changes in land values should be two-directional, and suggests using windfall profits from upzonings to pay for property value lost due to downzonings. Since most suits would be settled in a manner not involving compensation, the only real monetary winners would most likely be the lawyers. The courts, in decisions going back to at least 1922, have noted that government would be hard-pressed to function normally if compensation were required any time a decision had an adverse effect on property values. Only in cases where all developmental value is removed, the courts have said, should compensation be required.