37 CFR §41.203

1. (a)Interfering subject matter. An interference exists if the subject matter of a claim of one party would, if prior art, have anticipated or rendered obvious the subject matter of a claim of the opposing party and vice versa.
2. (b)Notice of declaration. An administrative patent judge declares the patent interference on behalf of the Director. A notice declaring an interference identifies:
   1. (1)The interfering subject matter;
   2. (2)The involved applications, patents, and claims;
   3. (3)The accorded benefit for each count; and
   4. (4)The claims corresponding to each count.
3. (c)Redeclaration. An administrative patent judge may redeclare a patent interference on behalf of the Director to change the declaration made under paragraph (b) of this section.
4. (d)A party may suggest the addition of a patent or application to the interference or the declaration of an additional interference. The suggestion should make the showings required under § 41.202(a) of this part.