A mechanic's lien is a lien given by statute to those who perform labor or furnish material in the improvement of real property. The law recognizes the right of the material man and laborer to hold for the amount of their claim the property to which they have added value and this right is in addition to the right of action against the person who made the contract of employment or purchase. The lien is specific as it affects only the property benefited, and it is governed by the provisions of the statute under which the right is obtained. A mechanic's lien is usually asserted by filing a notice of the claim with the county clerk. (Appendix form 1.) This notice must be under oath of the lienor or his agent and must set forth the claim in detail as to date, amount, location of property, etc., and must be filed within a certain time after the last material was furnished or the last labor performed. It then continues usually for a period of one year when it expires unless renewed for a further period by court order. The filing of the lien gives notice of it to all dealing with the property, and it is good against all except those whose rights are prior as shown by the public records. The lien is not affected by unrecorded instruments and would take precedence over a deed or mortgage given prior to, but not recorded until after the filing of the lien.

The right to file a mechanic's lien is given not only to the contractor dealing directly with the owner of the property, but is also given to sub-contractors. In Massachusetts, Pennsylvania, and some other States, the owner's property can be held for materials and labor supplied by a sub-contractor in accordance with the provisions of the original contract. This imposes upon the owner the obligation of seeing that the subcontractors are being paid by the general contractor in order to avoid liens upon his property and additional costs for the work performed. In most States, including New York, the law is that the sub-contractor is entitled to a lien on the property by virtue of his subrogation to the rights of the contractor-in-chief. Sub-contractors under this rule can hold the owner's property only for the amount due under the main contract - the one to which the owner is a party. If, however, the main contract calls for installment payments - that is, payments at certain periods or at certain stages of the work - and the owner anticipates these payments, he may be held by sub-contractors for the amount so anticipated. They can rely on his making payments only according to schedule and he deviates therefrom at his peril. Owners may also be held for payment of work done on their property with their consent and approval, either expressed or implied, even though the contract for the work was made by some other person, such as a tenant. The owner is not liable, however, for work done by a tenant without his knowledge or consent, nor is a remainderman usually liable for work done by a life tenant, and in such cases liens cannot be enforced against the owner's or remainderman's property.