Blank cheque

A blank check or carte blanche, in the literal sense is a check that has no monetary value written in, but is already signed. In the figurative sense, it is used to describe a situation in which an agreement has been made that is open-ended or vague, and therefore subject to abuse, or in which a party is willing to consider any expense in the pursuance of their goals.
Literal meaning.
Cheque writers are advised to specify the amount of the cheque before signing it. A blank cheque can be extremely expensive for the drawer who writes the cheque, because whoever obtains the cheque could write in any amount of money, and might be able to cash it (if the current account (US: checking account) contains sufficient funds, and depending on the laws in the specific country). Under American law, a blank cheque is an example of an "" as defined in the Uniform Commercial Code's Article 3, Section 115 (a). Writing an amount in a blank cheque, without the authority of the signer, is an "alteration". It is legally equivalent to changing the numbers on a completed (non-blank) cheque.
Metaphorical meaning.
In finance.
A "blank cheque company" refers to a company in development that has no specific business plan, such as a special purpose acquisition company.
In literature.
Sir Arthur Conan Doyle used the term "carte blanche" in several of his Sherlock Holmes stories.
<poem>"Then, as to money?"
"You have carte blanche."
"Absolutely?"
"I tell you that I would give one of the provinces of my kingdom to have that photograph."
</poem>
<poem>"I understand that you give me carte blanche to act for you, provided only that I get back the gems, and that you place no limit on the sum I may draw."
"I would give my fortune to have them back."
</poem>