There is of course a very well established right of privacy expressed in the Constitution and extending from Constitutional precepts dating back to the founding. The legal doctrine of Stare' Descisis is well established in that regard.

Now you ask where in the Constitution this right originates.
First up we see that in the original document there is no inclusion of the Bill Of Rights simply because the founding fathers saw no need to provide extra protection since those rights were spelled out in the body of the Const.
However some of the founders felt there might be a mis-understanding sometime down the road regarding personal rights so they all agreed to draft and ratify a Bill Of Rights specifically spelling out those rights and that is the document we have they passed down to us.
Now while the main body of the Constitution spells out what they government MAY DO and what it Must DO; the Bill Of Rights spells out what the government MAY NOT DO.
It Can't search or seize your property without due process.
It cannot hold you in prison without trial.
It Cannot enact laws abridging the rights of freedom of speech/freedom of religion/ the right to bear arms and various other prohibitions on the government are spelled out.
Then the Ninth and Tenth Amendments were enacted to make sure there was absolutely no mis-understanding concerning the LIMITED power of government granted by the Constitution.

Amendment IX The enumeration in the Constitution of certain rights shall not be construed to deny or disparage others retained by the people.

Amendment X The powers not delegated by the United States in the Constitution nor prohibited it by the states are reserved to the States respectively or TO THE PEOPLE.

Now; where is the right to privacy? It's right there in the BOR and those two amendments. The Government has no power to tell people what to do except in those areas specifically authorised in the Constitution.

You can't find the right to privacy spelled out in the Const.? You can't find any right to be married or any right to own stock or play golf or be a member of the Communist Party. Because you have those rights by definition.

So again what is legislating from the bench mean?