I thought capital requirements for the GSEs were set by statute in 12 USC 4612:
"For purposes of this subchapter, the minimum capital level for each enterprise shall be the sum of—
(1) 2.50 percent of the aggregate on-balance sheet assets of the enterprise, as determined in accordance with generally accepted accounting principles..."
As of 6-31-14, FNMA had total assets of $3,218 B and equity of $6.1 B or less than .2%. But with the remaining credit line from Treasury under the SPSA ( about $83 B), one could argue under sec. 4502 (23) that FNMA has total capital of $89 B available under conservatorship or 2.76% which meets the statutory minimum. Note that FNMA had cap ratios of 4.66%, 4.92%, and 4.98% before the crisis for YE 2005-07.
While I agree plaintiffs are likely to prevail in court, you are correct that the consequences of a victory are uncertain -- and that's what gives me pause from increasing my position. Bad case scenario:
1. plaintiffs win
2. Treasury ordered to return $80 B.
3. Treasury terminates the SPSA under sec 6.7 and/or 6.12, and demands full repayment
4. FHFA deems the GSEs critically undercapitalized and converts them to a receivership.
Obviously there are other possible scenarios, but it's obvious that we need Treasury cooperation/support even if the cases are won.