What is the ruling on a case
when, if you tell a man or a woman, “What you are doing is haraam” –
such as telling a woman not to wear short clothes, or telling a man not to
smoke cigarettes – they reply by saying that everyone does that, or that
all the women in our country dress this way?

Praise be to Allaah. 

The
response that you describe is wrong, and the people’s evil actions
cannot be justified. Allaah says (interpretation of the meaning):

“And
if you obey most of those on the earth, they will mislead you far away
from Allaah’s path” [al-An’aam 6:116]

Rulings on
what is halaal and what is haraam are taken from the Book of Allaah and
the Sunnah of His Messenger
(peace and blessings of Allaah be upon
him), not from what people do, because people may be wrong or they may be
right.