One of the important rules of Vinaya, for Buddhist monks as well as nuns, is the prohibition of a monk to be alone with women, and a nun to be alone with men. This is not just a rule for strict monks and nuns, but a rule which the Buddha made obligatory for all monks and nuns. Since this is a rule which often comes up, I will explain it at length in this Vinaya article.
In the introduction to one of the rules ("Aniyata" 1) found in the Vinayapitaka, there occurs the following story:
"At one time the Enlightened One, the Lord, was staying at Savatthi in Anathapindika's Park, in the Jeta Grove. Then the Venerable Udayin approached this girl (a newly married daughter of one of Ven Udayin's supporters) and having approached her, he sat down together with that girl, one man and one woman, in a secret place on a secluded, convenient seat, conversing at the right time, speaking Dhamma at the right time ... Visakha (the famous lay woman disciple) saw the Venerable Udayin sitting together with that girl, one man and one woman, in a secret place on a secluded convenient seat. Seeing this, she said to the Venerable Udayin: "This is not proper, honoured sir, it is not suitable, that the master should sit together with womenfolk, one man and one woman, in a secret place on a secluded, convenient seat. Although the master has no desire for that thing (sexual intercourse), unbelieving people are difficult to convince." The Venerable Udayin took no heed of Visakha..... Visakha told this matter to the monks ... The monks became vexed, annoyed and angry and told the matter to the Lord ... The Lord rebuked Ven. Udayin: "How can you, foolish man, sit together with womenfolk, one man and one woman, in a secret place on a secluded, convenient seat?
..."(The Lord Buddha then laid down a rule explaining...)
'A secret place' means secret from the eye, secret from the ear. Secret from the eye means if (the monk) covering his eye, raising his eyebrow, raising his head, he (the onlooker) is unable to see (the monk). Secret from the ear means he (the onlooker) is unable to hear ordinary speech. 'A secluded seat' means it is secluded by a wall, or by a door, or by a screen, or by a screen wall or by a tree or by a pillar or by a sack or it is concealed by anything whatsoever. 'Convenient' means it is possible to indulge in sexual intercourse."
(from the Pali Text Society's Book of the Discipline, Vol l, p 330ff)
The following rule, "Aniyata" 2, is similar to the first, which I have just described, with the only change being that this time Venerable Udayin sat down with that same girl, just the two of them, in a secret place (secret from the eye, secret from the ear), that was not a secluded place (by a wall etc) nor a convenient place (for sexual intercourse). Again when Visakha spotted Venerable Udayin and the girl alone together, she rebuked the monk:
"This, honoured sir, is not right, it is not suitable for the master to sit together with womenfolk, one man and one woman, in a secret place. Although, honoured sir, the master has no desire for that thing (here referring to flirting), unbelieving people are hard to convince."
Again Ven. Udayin took no heed of Visakha's complaint, so she told the monks who told the Lord Buddha. The Buddha then rebuked Ven. Udayin and condemned such behaviour by establishing another rule for monks.
The above quotations, directly from the Vinayapitaka, show the danger of a monk being alone with women, especially inside a room, car or building. These rules were repeated in the nuns' Vinaya, prohibiting a nun being alone with men for similar reasons. In today's society where allegations of sexual abuse are rife, and are often just one person's word against another's, keeping these important rules is more than just a protection from the opportunity for abuse, but also a guard against the suspicions spread by the malicious. Suspicions, even when untrue, are so difficult to disprove. As the wise laywoman Visakha said "Even if the Venerable monk or nun has no desire for that thing, unbelieving people are hard to convince".
Knowing this rule now, may we help all Buddhist monks and nuns keep their precepts well and thus help prevent allegations that are damaging to all. Please avoid being alone with a monk if you are a woman and if you are a man, avoid being alone with a nun. Thank you.