Private property may be taken for public uses under the State's right of eminent domain. This right may be exercised by the United States Government, by the States and counties, and also by cities and villages upon which the right has been conferred. The right of eminent domain is also conferred upon public service corporations, such as railroads, and telegraph companies, whenever a public purpose is to be served by their acquiring the land. Our constitution places a safeguard upon the rights of private property in that it guarantees that no property shall be taken except by due process of law and payment of just compensation. Due process of law includes notice to the owner and a just trial.

The proceeding by which property is taken for public uses is called a condemnation proceeding. In the case of public service corporations this proceeding may include proof by the corporation of the necessity for taking the land, but this usually does not have to be done when the land is taken by a direct governmental agency. In almost every case, the real issue to be tried is the amount of compensation to be paid the owner for the property taken. Trial is usually held before a court or before a commission appointed by a court. The proceeding also includes the assessments of the cost upon the property benefitted.

The work of the expert appraiser in condemnation proceedings consists in giving testimony before the court or commission of the value of the property condemned. Experts are usually retained by the owner and other experts by the corporation or public authorities interested. The owner wants to get as much as possible for his property, and the other side wants to pay as little as may be necessary. The experts are placed on the stand and examined as to their qualifications to act as experts and to place upon the record their opinions regarding the valuation of the property under condemnation. The examination will bring out the familiarity of the witness with the neighborhood and his personal knowledge of sales of similar property actually made. He may have to make use of the Davies or Hoffman rules, the cost of buildings, the rental value of the property, and the adequacy of the improvement. He may also have to testify as to special features pertaining to the property, tending to increase or reduce its value. Witnesses are cross-examined by the opposite side, and efforts are made to minimize the value of their testimony or to detract from its weight. The proceeding may become a battle of experts. The expert on the stand requires not only the knowledge and experience to give weight to his testimony but also the ability to conduct himself properly under examination and cross-examination. He is testifying as an expert to a valuation computed on the basis of a definite theory. He should adhere to this theory in order to be consistent and not become confused. For figures, he should refer to notes. He should be patient and courteous yet at the same time have his wits sharp to parry questions designed to trap him.

It may be noted that on direct examination the witness, in most States, cannot testify regarding other sales in order to support his opinion of value. Cross-examination by opposing counsel may seek to bring in testimony of sales which apparently tend to show a less value than that stated by the witness, but re-direct examination will endeavor to have the witness show special features of such sales and will ask him questions regarding other sales which help the case.

If the testimony is taken before a commission, an award is made to the owner and embodied in a report to the court. The opportunity is given to both sides to state objections. The court may confirm the award or if it sees fit may send it back to the commission for a re-hearing or may appoint a new commission to hear the testimony.