I'm not sure what you mean. Deadweight loss is tautological. Maybe you're asking for evidence that taxes distort markets? If you accept that as true it's easy t

I'm not sure what you mean. Deadweight loss is tautological. Maybe you're asking for evidence that taxes distort markets? If you accept that as true it's easy to see that deadweight loss is just the difference in surplus before and after the tax. Every econ paper on tax policy will try to measure the deadweight loss of the intervention.