If no taxes are owed, can you still claim a refund on gambling losses?

Gambling losses are deductible only to the extent of gambling winnings - if you win $100,000 and lose $20,000 - then you can deduct the $20,000 from the $100,000 paying tax on $80,000. But if you win $100,000 and lose $150,000 (a circumstance far more common), then you have no taxes on the winnings and no deduction for the "excess" losses.