Yes, there is such a law.
Can. 1171 Sacred objects, which are designated for divine worship by dedication or blessing, are to be treated reverently and are not to be employed for profane or inappropriate use even if they are owned by private persons.
An alb certainly falls under that definition of an object designated for divine worship by blessing.
Now, whether or not any individual alb has indeed been blessed is (of course) an unknown, however every alb used at Mass certainly should be blessed. Regardless of whether or not the blessing was omitted, once a vestment is used at Mass it still falls into that same category.
As a priest I deal with this question rather frequently. People want to use sacred vestments (sometimes even other objects like chalices) for all kinds of non-liturgical purposes such as Christmas pageants, plays, halloween costumes (thankfully, that doesn’t happen often), etc. The answer is always a firm “no” followed by the explanation that since that particular item has been blessed and dedicated for use at the Mass, then no other purpose* can ever be appropriate.
Having said that, if you are willing to purchase a new alb and use it as part of your costume, there would be nothing wrong with that. Some rather inexpensive ones are available from most catalogues.
I’m anticipating all kinds of “I did it” or “my friend did it” type of responses here, so I’ll post the following:
Just because you saw someone do it, that does not make it right.
- by “no other purpose” I do not mean to exclude purposes connected to the Liturgy of the Church. Surely, an alb can be worn at a baptism, or to take Holy Communion to the homebound, Stations, etc.
