When we consider the laws relating to marriage formation, it is traditional to consider the formalities for marriage, that is, laws relating to the legal age for marriage, the locations in which it is possible to marry and relevant requirements for a legally valid ceremony. All of the foregoing have undergone significant changes with the introduction of the Civil Registration Act 2004 and relevant amendments to this principal Act in the years since it was enacted. However, what is given far less, if any, attention are the criminal offences which relate to marriage formation. While many may instinctively think of the offence of bigamy in this context, in recent times, there is even further involvement of the criminal law in this area, namely, increasing attempts to prevent so-called “sham” marriages or marriages of convenience and recent legislative intervention to create a new offence of “forced marriage”. These criminal law interventions are very important to tackle illegal and harmful activity and prevent the institution of marriage being abused to take advantage of vulnerable individuals. However, in the Irish context, where marriage is specifically protected in the Constitution, with the State pledging in Article 41.3.1 to guard it with special care, it will be seen that protecting the institution is also an important function of the criminal law in this area. With this in mind, this article reflects on the current criminal laws connected to marriage, namely, the laws relating to bigamy, marriages of convenience and forced marriage. In relation to each area of law, the article considers recent developments and avenues for future progress and reform.