For citizens in danger of losing property rights, the first question to ask in this area of law is "What qualifies as a takings?" Clearly, where the government converts an individual's property into public land, forcing the individual to move, a takings has occurred (this is referred to as a "physical invasion"). But not all takings are this easy to recognize.
For example, in Lucas v. South Carolina Coastal Commission, the United States Supreme Court found that an individual was entitled to compensation where the government had subjected his land to such extensive regulation that it no longer had any viable economic use. Thus, even though the government did not physically take the individual's property, he was entitled to compensation for the manner in which the government regulated his land.
In Lucas, the Supreme Court held that a regulation which deprives an owner of all economic use of his land will always qualify as a takings. This rule now accompanies the prior standard from Pennsylvania Coal Co. v. Mahon - that a regulation which goes "too far" will qualify as a takings. In this setting, a landowner subject to government regulation will want to show that their land has no economic value left, since that type of regulation will always qualify as a takings. In contrast, the government will likely try to regulate land in a way which does not deprive an owner of all economic uses.
But even if an individual's land has economic use left after the government's action, they could still try to prove that a regulatory takings occurred using the Pennsylvania Coal Co. standard. While this rule is very murky, it gives the landowner an opportunity to show that the government's regulation went "too far." If successful, the landowner would be entitled to compensation for the government's actions. Thus, landowners who have lost property rights due to government regulation may want to consider legal action, as they may be entitled to compensation for their loss.