Using back end of a r/t airline ticket

I don't think so. My understanding is that if you don't show up for the first leg, the airline has the right to cancel the entire ticket.

Thanks, I was afraid so. I found airfare for 418.00 leaving April 12, and return good for 12 months. I need to leave on June 20, and can use stand-by tickets to go, but coming back in July is embargoed so I must buy a ticket home. One way is really expensive, and r/t not much less, flying in July. I was hoping I could by the cheap ticket today, and use the back end in July.

I wouldn't risk it, John. The airline can cancel the remaining legs of a trip if you don't show up for one. Then you would be stuck buying a new ticket at that day's prices (if it's available) to get home.

If you fail to use the first leg - out bound - the whole ticket is canceled. You could get away without using the return leg. In theory the airline has the right to charge your for a one way ticket but the probability of them doing so is very remote.