A more thorough explanation:

Contra formam collationis is a Latin term that means "against the form of a collation." In history, it refers to a writ that was used to regain lands that were given to a religious society in exchange for perpetual alms. This writ was usually sought by an heir of the person who had given the land away.

For example, if a wealthy landowner gave a piece of land to a religious society in exchange for the society's promise to provide perpetual alms, the land would be transferred to the society. However, if the landowner's heir later wanted to regain the land, they could seek a writ of contra formam collationis to challenge the legality of the transfer.

Another example would be if a king granted a piece of land to a religious order, but the grant was later challenged by a noble who claimed that the king did not have the authority to make such a grant. The noble could seek a writ of contra formam collationis to challenge the legality of the grant.

These examples illustrate how the writ of contra formam collationis was used to challenge the legality of land transfers to religious societies. It was a way for heirs or other interested parties to regain control of land that had been given away in exchange for perpetual alms.