Cadastral or Legal surveying deals mainly with the establishment or relocation of land boundaries. According to law, only licensed land surveyors can establish the locations of boundaries and carry out legal surveys.

Legal surveys are usually made for one of the following reasons:

1. To acquire the data needed to write a legal description of a specific parcel of land,
2. To re-establish the boundaries of a parcel of land for which a survey has previously been done, or,
3. To subdivide a parcel of land into various pieces according to a specific plan showing the predetermined size, shape and location for each parcel.

Whenever real estate or property is sold or passed from one person to another it is important to know and define the location of the boundaries. For this reason, the legal or licensed land surveyor must be familiar not only with technical aspects of surveying, but also the legal aspects of real property and boundaries.

The duties of a license land surveyor include:

• Conducting the field survey and measurements,
• Calculation of dimensions and areas of land being surveyed,
• Preparation of maps detailing the boundary lines and areas of lands, and
• Writing legal descriptions of land parcels.

Legal surveys are typically horizontal plane surveys.