An agreement under seal can only be dissolved ea ligamine quo ligatur.

Explanation

(English-origin maxim.) A contract made under seal can only be dissolved by an instrument of equal solemnity — what is bound by deed must be released by deed.

Where this applies

• A property deed executed under seal can only be voided by another document under seal — a casual letter or verbal agreement cannot undo it.
• Two parties entered into a sealed bond, and one tries to release the other by a simple handshake, but the court requires a formal release under seal.
• A corporation's charter, executed as a sealed instrument, cannot be amended by an informal board resolution — it requires a document of equal formality.