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BDSM would be allowed- even to the Orthodox! There is a ruling that anything that enhances the relationship between a husband and wife is allowed. Their are some elements of BDSM that would nto be allowed though:

Cross dressing- men wearing women clothes, or women wearing mens clothes is an activity that is strictly forbidden in the Torah

Polyamory- (a relationship with more than two people)- Judaism does not allow relationships with more than one partner

Branding/tattooing- not allowed

Piercing nipples would be allowed for women but not for men, as such jewellery is considered to be part of women's clothing and forbidden as per the cross dressing above

Now, as stated above, most BDSM activities would be allowed even to an Orthodox couple, but a couple of considerations would normally prevent it

1) Sex with the lights on= many sources, while encouraging sex and enjoyment of sex, state it should be done in the dark or in indirect light only. This is so that the physical appearance and contemplation of the body should not be the main driving force- rather the person and their needs should be paramount.

2) Too much immersion in the physical is seen as bad. If BDSM play is just going to be the same duration as other sexual activities- not an issue. But frequently it is longer, especially with various role play scenarios

Now, many people may be wondering at my knowledge LOL Simply put- as I have stated before I became religious when older and was involved in various 'other" activities when younger...

edit: Joshua Rambam specifically allows a husband and wife to have sex in ANY manner! He says it is not good, and that it is the way of chassidus not to indulge in some practices, but that it is allowed.

Hilchos Issurei Biah, Chapter 21

י [ט] אשתו של אדם, מותרת היא לו; לפיכך כל מה שאדם רוצה לעשות באשתו, עושה--בועל בכל עת שירצה, ומנשק בכל אבר שירצה, ובא עליה בין כדרכה, בין שלא כדרכה, בין דרך אברים. ואף על פי כן, מידת חסידות שלא יקל אדם את ראשו לכך, ושיקדש עצמו בשעת תשמיש, כמו שביארנו בהלכות דעות; ולא יסור מדרך העולם ומנהגו, שאין דבר זה אלא כדי לפרות ולרבות.

Now, we do not pasken according to Mishneh Torah- neither this ruling or the ruling from Hilchos Deot. This ruling is contentious in various aspects, not least the fact that he explicitly allows anal sex (בין שלא כדרכה) and other practices that the other Rishonim forbid! However, we do pasken that outside of explictly forbidden practices, a husband and wife can indulge in whatever sexual activities, and frequency of sexual activity, they desire- though as the Rambam states above- what is allowed vs what would be considered the ways of Chassidus are different!