In an article today in The Freeman on-line, economist Steven Horwitz makes a case for allowing same-sex marriage. In doing so he makes the following statement:

Government must treat all its citizens equally, and nothing paid for with tax dollars may involve invidious discrimination.

I hasten to point out that I agree with his bottom line about allowing same-sex marriage. What I’m not sure of is his general principle quoted above. What one person regards as “invidious discrimination,” another will regard as justified discrimination.

Consider an example that my co-blogger Bryan Caplan and I (here, here, here, here, and here) have argued about and that he has convinced me on: means testing for government benefits. I had originally argued against it. That struck me as, in Steve’s terms, “invidious discrimination.” Take two people who earned the same annual wage or salary all their lives. One spent a lot of it on trips to Europe every year. The other one saved. At age 66, the one who took trips to Europe had no income from dividends, interest, or capital gains. The other one had substantial income in those three categories. Because the usual method of doing means testing is to consider annual income, the saver will be screwed by means testing. That was enough to convince me that means testing is wrong.

But if you read the last two posts cited above, you’ll see how Bryan persuaded me. I wonder which side Steve would favor. Means testing means explicitly violating equality before the law. Equality before the law is not as straightforward a principle as Steve seems to think.