A structure that lawfully existed before the current zoning bylaw is best described as a:

The correct description for a structure that lawfully existed before the current zoning bylaw is "legal non-conforming structure." This term refers to buildings or uses that were compliant with the zoning regulations at the time they were established but do not meet the current zoning requirements due to changes in the law or regulations. The key aspect here is that the structure was legally permissible when it was built, which allows it to continue existing even though it may not conform with the latest zoning laws.

This distinction is important in land use planning and zoning, as it provides certain protections to property owners, allowing them to continue using their property in its existing manner without facing penalties, despite changes in zoning laws. Understanding this concept is essential for real estate professionals in navigating the complexities of property rights and zoning regulations.

The other terms mentioned have different implications. For example, a "grandfathered structure" is commonly used colloquially to describe similar situations, but "legal non-conforming structure" is the more technical and accurate term used in legal and planning contexts. Other terms like "historical property," "legally exempted structure," "pre-authorized structure," and "protected designation structure" all refer to specific legal statuses or designations that do not apply to structures