The worst idea in American politics right now may be the effort by some Republicans in Congress to end birthright citizenship – the constitutional fact, under the 14th Amendment, that a person born in the United States is a U.S. citizen.

I do not know the intentions of the politicians advancing this argument, but let’s assume they are well-intentioned people, who believe they are preventing illegal immigration with such a policy change.

Here’s what they also would be doing, perhaps unwittingly: establishing a new American system of apartheid. Think about it. Some people born in the United States would be citizens, because they are born to U.S. citizens. Others born in the U.S. would not be citizens, presumably, if one or both parents were not permanent legal residents of the country.

That means that people’s legal status and rights would depend not on who they are but on who their parents were.

That is profoundly un-American.

One of the reasons this country works – and why it has been not only a magnet for immigrants but also a place that integrates immigrants more effectively than virtually any other human society – is that citizenship is universal. If you’re born here, no matter who you are, you’re a citizen. If you come here and follow the rules and make it through the same application process as everyone else, you’re a citizen. One reason immigrants integrate relatively easily here is because they want to integrate, and they want to integrate because they know they can become Americans and because they know their children and grandchildren, by virtue of being born here, will be Americans.

The Republicans who want to end birthright citizenship would wipe away these bright lines and blow up a relatively simple system.

If they succeed, they will need more lawyers and more courts and more government bureaucrats to process millions of new citizenship applications – and judge all the disputed cases that will arise over citizenship. (Imagine the difficulty of adjudicating all the confusions and disputes that will arise over paternity, when paternity determines whether or not you’re a U.S. citizen).

And don’t forget the extraordinarily high political costs of such a policy for its backers, who would have effectively declared war against immigrant families – and future Americans.

Much smarter for Republicans to kill this bad idea now, in the cradle.