"The Secretary is authorized to purchase, and to make and fund commitments to purchase, on such terms and conditions as determined by the Secretary, mortgage-related assets from any financial institution having its headquarters in the United States.
[...]
The Secretary’s authority to purchase mortgage-related assets under this Act shall be limited to $700,000,000,000 outstanding at any one time.
[...]
Decisions by the Secretary pursuant to the authority of this Act are non-reviewable and committed to agency discretion, and may not be reviewed by any court of law or any administrative agency."

-- Draft Legislative Proposal for Treasury Authority to Purchase Mortgage-Related Assets