The American Civil Liberties Union is accusing Morgan Stanley of fueling the production of risky, expensive loans that targeted African-American borrowers.

In the lawsuit, filed on Monday, the A.C.L.U. claims that Morgan Stanley is culpable for predatory loans made through the New Century Financial Corporation because the investment bank lent billions of dollars to New Century, a now-defunct subprime lender, and pressured it to make troublesome loans to African-American borrowers who could not afford them.

Morgan Stanley packaged the loans made by New Century and sold them to pension funds and other large investors. But, the lawsuit claims, the bank went beyond the traditional role of an investment bank by requiring that the mortgage company churn out the wildly profitable loans that came with “dangerous” characteristics.

For example, the lawsuit says, many of the loans ultimately sold to investors were “stated income” loans, in which borrowers could estimate their incomes without having to provide supporting documentation.