Sovereign immunity is a pretty well settled concept at the Federal level (especially with regard to law enforcement and foreign relations), with a few exceptions.

As a result, even if all of the plaintiff's claims were factually true as alleged--the posture assumed in pre-trial motions--I believe the agents acting in their official capacities would likely be found to have immunity.

There is the possibility of a Section 1983 claim against the officials if 4th amendment rights were found to be violated (which the Court has allowed), "[b]ut government officials performing discretionary functions generally are granted a qualified immunity and are 'shielded from liability for civil damages insofar as their conduct does not violate clearly established statutory or constitutional rights of which a reasonable person would have known.' Harlow v. Fitzgerald, 457 U.S. 800, 818, 102 S.Ct. 2727, 73 L.Ed.2d 396 (1982). Wilson v. Layne 526 U.S. 603, 609, 119 S.Ct. 1692, 1696 (U.S.Md.,1999)." [1]

[1] http://www.robertslaw.org/4thamend.htm