The gemara (Sota 7b) derives that a sotah can be tried only in the "supreme court" beis din of 71 people through a gezeirah shava that connects the parsha of sotah to that of zakein mamrei, who we know is tried in a court of 71.
I would like to suggest that the gemara is not simply a technical limud that tells us the number of judges required, but rather reveals that there is an underlying thematic relationship between the two parshiyos. Both sotah and zakein marei are crimes of rebellion against authority -- in the latter case, against the authority of beis din; in the former case, against the authority of the sotah's husband. The parsha of sotah does not use the terminology used for crimes of arayos, "lo tikrivu l'galos ervah," that we are familiar with from other contexts where the Torah discusses forbidden relationships. Instead, the crime is describes as "ma'alah ma'al b'isha," the sotah has sinned against her husband.
This approach makes for a very patriarchal reading of the parsha. Whether that troubles you or not (and how to deal with the issue if it does) is up to you (much has been written about the issue) -- I'm just making the observation.