The "one penis policy" (OPP) refers to an arrangement in CNM, most often associated with couples opening up, where a male-female couple agrees that the female partner may have relationships with women or non-binary people, but not with other men. The male partner may or may not have symmetrical restrictions.
The term is sometimes used mockingly in polyamory communities, but it describes a real and common arrangement that deserves honest analysis rather than simply ridicule.
Why it exists
The OPP typically emerges from a specific combination of insecurities and assumptions in a newly opening male-female couple:
The male partner's jealousy is more activated by the prospect of his partner with another man than with a woman. This may reflect internalised assumptions about what constitutes "real" sex or "real" threat to the relationship, cultural scripts about male competition for female partners, or simply how that person's jealousy happens to work.
The assumption, often unstated, that female-female or female-nonbinary connections are less emotionally significant or less threatening than connections with men. The word "just" often appears: "she can see women, just not men."
A desire to open the relationship that's more asymmetric than it's presented: the male partner wants the freedom to pursue female partners outside the relationship but is less comfortable with his female partner having equivalent freedom.
Why it's contested
The OPP receives significant criticism in polyamory communities for several interconnected reasons:
It's structurally sexist. The arrangement restricts the female partner's connections based on the gender of potential partners, while the male partner typically has fewer or no such restrictions. This asymmetry usually reflects the male partner's insecurities being treated as more important than the female partner's autonomy.
It's biphobic in effect. The assumption that female-female connections are less significant devalues bisexual women's same-sex relationships, treating them as less real, less potentially threatening, and therefore more permissible. This is a specific form of bi erasure.
It doesn't work as intended. The assumption that female-female connections are emotionally "safer" than male-female ones tends not to hold in practice. Deep emotional and romantic connections develop regardless of partner gender. Relationships designated as non-threatening because of partner gender don't stay non-threatening once genuine feelings develop.
It frames the female partner's autonomy as conditional. The arrangement positions the male partner's comfort as the determining factor in what connections his female partner is permitted to have, a structure that resembles control more than negotiated agreement.
The legitimate concern it's trying to address
Being honest about this: the jealousy that produces OPP requests is real, even if the way of addressing it is problematic. A person who finds same-gender connections less activating than different-gender ones isn't wrong about their own emotional experience, they're responding to how their jealousy actually works.
The more productive approach to that jealousy isn't to restrict the partner's connections by partner gender, but to work directly on the jealousy: understanding what specifically triggers it, whether those triggers are proportionate, what needs the jealousy is expressing, and whether there are ways to address those needs that don't require restricting the partner's autonomy.
What it usually produces
OPP arrangements tend to have specific failure modes. The female partner develops a deep connection with a woman or non-binary person that turns out to be every bit as emotionally significant as the male partner feared; the OPP didn't protect him from the thing he was trying to protect against, it just rerouted it. Or the female partner eventually finds the arrangement untenable and the couple has to renegotiate from a more conflicted position.
The more honest version of the arrangement, "I'm not ready to process jealousy around the idea of you with another man right now, and I'd like to start with this limitation while I work on that", with an explicit commitment to doing that work and revisiting the arrangement, is different from the OPP as typically framed. The former is a temporary accommodation of a known limitation; the latter is a structural restriction that tends to be defended as permanent.