I'm not an expert in patentese, but here's what I found:

Klage auf Erklärung der Nichtigkeit erhoben
An action for the declaration of nullity has been brought

This link might be helpful: https://dpinfo.dpma.de/hilfe/vstdpat_hilfe_trans.html

G.R. No. L-61113An action for annulment of a patent and for reversion of the land to the State may be filed only by the Solicitor General as provided in Section 101 of Com. ...
www.lawphil.net/judjuris/juri1990/feb1990/gr_l_61113_1990.h...

Table 3 shows the actual outcomes of opposition and annulment procedures in the case of the 1977 application year cohort. In the sample used here, 8.4 percent of all patents encounter opposition. The annulment procedure (Nichtigkeitsverfahren) occurs at a much lower frequency in 0.3 percent of all cases in which a patent was granted initially. Opposition may be held inadmissible in which case it has no consequences for the patent-holder; it may lead to a restriction of the scope of the patent; or it may lead to the patent being upheld completely.
http://emlab.berkeley.edu/users/bhhall/harhoffetal99.pdf


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Note added at 1 hr (2009-02-24 19:20:08 GMT)
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Cancellation Proceeding
Definition:
A proceeding before the Trademark Trial and Appeal Board in which The plaintiff seeks to cancel an existing registration of a mark.
http://tinyurl.com/cggog8

What is a cancellation proceeding?
A cancellation proceeding is initiated by a party who is seeking to use a mark which is currently registered by someone else, or who believes that it is being (or will be) damaged by that registered mark. This proceeding is initiated by the party filing an application with the Trademark Trial and Appeal Board. The Board will then notify the trademark’s owner that a cancellation proceeding had been initiated.
A cancellation proceeding is a proceeding between the two parties (the trademark owner and the challenging party) that runs much like an in-court lawsuit. During the course of this proceeding, the parties will exchange evidence regarding their respective trademarks and other issues relevant to the cancellation proceeding. They will ultimately file briefs with the Board, which will review these briefs and make a decision as to whether the trademark should be canceled. If the Board determines that there is a valid ground for cancellation of the mark, the trademark will no longer be registered and the owner will no longer be entitled to exclude others from using the mark under the federal trademark scheme (but there may still be state rights in the mark).

http://www.quizlaw.com/trademarks/what_is_a_cancellation_pro...

Example: http://www.std.com/obi/USG/Patents/part3 "Recommendations directed at post-issuance improvements included establishing streamlined reexamination procedures, or establishing a nullification procedure either within or outside of the USPTO."

and used in the Court context:
http://www.managingip.com/Article.aspx?ArticleID=1321758 (description of metropolitan court decision)

I am afraid I cannot agree with the answer already given, of "nullity procedure", because "procedure" sounds a bit strange. It is normally "nullity proceedings".