Case in point | Is consummation a legal oddity?

The consummation of marriage has historically been a source of legal oddity. Take France, where from 1550 to 1667, virility was proven through 'trial by congress', sexual intercourse in front of witnesses. And manual arousal by expert witnesses to test the alleged impotency of husbands was not unknown in England's mediaeval consistory courts: Russell c. Scathelok (York, 1433), BI, CP.F.II.

But as marriage is being redefined by the Marriage (Same Sex Couples) Bill, the question of consummation's place in the modern world has been raised. Might consummation prove to be a niggling inequality in the proposals for same-sex marriage? Why is the law wary of allowing non-consummation to annul gay marriages? And why does the law still require a sexual seal on conjugal unions anyway? Would the removal of consummation as a validating element of marriage be itself a consummation devoutly to be wished?

Opposite-sex marriages may be nullified if unconsummated either because of a spouse's incapacity or wilful refusal to do so. Curiously, the Marriage (Same Sex Couples) Bill excludes same-sex marriages from nullification by non-consummation.

Defining 'consummation' has been a somewhat casuistic exercise. Dr Lushington in D v A (1845) 1 Rob Ecc 279 thought consummation to be "ordinary and complete intercourse". After hearing that the respondent's vagina was an "impervious cul de sac incapable of expansion" to allow penetration to a depth greater than two inches, Dr Lushington declared D's and A's marriage void.

If 'ordinary' intercourse is penile penetration of the vagina, what 'completes' intercourse? Sadly for the respondent in W (Orse K) v W [1967] 1 WLR 1554, although able to "penetrate [his] wife for a short time [,] soon after he got inside her, his erection collapsed and he came out". His ephemeral entering of his wife was perhaps "ordinary" but was not "complete". In Grimes v Grimes [1948] P 323, Finnemore J held that coitus interruptus was no vera copula: consummation required "emission" within one's wife. Two days later though, Wilmer J in White v White [1948] P 330 deemed ejaculation not to be a prerequisite of consummation. And, bizarrely, in Snowman v Snowman [1934] P 186, despite the petitioner's pregnancy by her husband, consummation had not taken place because penetration had not occurred. With Latinate delicacy, Bateson J in Snowman found that "fecundation [had] taken place ab extra".

So, consummation requires a more than transient penetration of the vagina by the penis, with or without internal ejaculation. Anal or oral sex, digital or lingual penetration of the vagina or frottage cannot then consummate marriage. And therein lies the rub for same-sex marriage. Only penile penetration of the vagina rather than another orifice is recognised by the law. And the case-law's phallocentrism would appear to exclude all possibility of lesbian consummation. Perhaps judges could "develop, over time, a definition as to what constitutes same-sex consummation" as the Government Equalities Office concluded in March 2012.

Why omit consummation as an ingredient of a valid same-sex marriage? Consummation's reproductive potential cannot be the answer: the possibility of procreation is certainly not an element of consummation in straight marriage (Baxter v Baxter [1948] A.C. 274). The Marriage (Same Sex Couples) Bill might simply mirror the law on civil partnerships, which cannot be nullified by non-consummation. But why are civil partnerships not voidable by non-consummation? Perhaps there is a lurking discomfort on the part of the legislature to elevate homosexual sex to the same privileged state as heterosexual sex. The law's continued failure to include homosexual sex within the definition of adultery certainly suggests so. Heterosexual sex is sacred enough to render a couple 'one flesh' when they marry and is powerful enough to end a marriage should a spouse stray. Homosexual sex, however, neither anoints a gay couple's union nor, when extra-marital, destroys it. The discrepancies between same-sex marriage and opposite-sex marriage might well be incompatible with the rights to private and family life and the right to marry enshrined in articles 8 and 12 along with article 14's prohibition against the discriminatory enjoyment of those rights.

But should the absence of sex be sufficient to nullify any marriage, gay or straight, especially as impotence or frigidity might constitute the unreasonable behaviour needed to petition for divorce? The Law Commission last gave its views on consummation in 1970. Nullification based on non-consummation should be retained, said the Law Commission 43 years ago, because conjugal rights were the pillars of marriage. However, the ancient 'marriage debt' is an unpleasant duty to place at the centre of marriage, especially as forced 'payments' were once allowed to be extracted. Rape could not be committed within marriage when the Law Commission made its recommendation for nullification by non-consummation to remain. The recognition of marital rape in R v R (A Husband) [1992] 1 A.C. 599 suggests that conjugal rights are now no longer an esteemed part of marriage.

An answer to the consummation '¨question might be found north of the border. The Scottish Law Commission recommended over two decades ago the abolition of nullification based on impotency. And the Scottish government, when considering same-sex marriage last year, saw merit in abolishing nullification due to impotency to avoid inequality between gay and straight marriage.

Perhaps consummation will be abrogated as a legal concept leaving only a prurient stain in the law's history.