BP has established a $20 billion escrow fund to pay claims filed by individuals and businesses adversely impacted by the spill. If people do not take an escrow payment, then their claims will be handled in one of the 300 proposed class action/shareholder suits.
If those harmed by the spill are also claiming damages projected into the future, their experts will first need to project the future lost profits. Then the experts will need to discount those projections at an appropriate (risk-adjusted) discount rate to calculate damages as of the date of the spill or the date of trial (whichever is deemed appropriate).
In either event, discount rates arrived at using a total beta perspective will carry much more weight with the finder-of-fact than other approaches, which require a complete guess as to the appropriate company-specific risk premium - at least in my opinion.