Although there are good political reasons for conservatives to be pro-immigration, the best reasons have to do with principle. When I was learning how to be a Reagan Republican, you did not have to be against immigrants and you were supposed to be in favor of refugees. Support and encouragement of a robust legal immigration system—not just for immediate relatives of U.S. citizens and the occasional rocket scientist, but for thousands upon thousands of ordinary people seeking better lives—flows naturally from the positions most conservatives take on related issues.

Opponents of immigration are fond of dismissing pro-immigrant conservatives as “big business” seeking “cheap labor.” The germ of truth in this is that American conservatives generally believe that economic activity should be governed by contract rather than by status. We believe an economic system driven by competition among free individuals and enterprises is more likely to confer long-lasting benefits on everybody than a system in which government periodically designates winners and losers…

The anti-immigration movement and its conservative supporters are right to believe we should have better immigration enforcement. We are now sending exactly the wrong message to prospective immigrants: Don’t even think about coming here legally, unless you are in one of the relatively narrow legal immigrant categories. But if you come here illegally, we probably won’t catch you. Both parts of this message need to be fixed: by enforcement that is thorough and effective without being mean, and by a far less restrictive legal immigration system.

The recent bipartisan proposal by Sen. Marco Rubio and seven of his colleagues, which has been the starting point for the current negotiations, gets an astonishing amount of this right. In particular, it takes exactly the right approach to the question of “amnesty.” The proposal recognizes, on the one hand, that people who violate immigration laws are more like speeders than they are like murderers. Violations of law should not go unpunished, but penalties should be proportionate, and a substantial fine is appropriate for most immigration violations.