Right now, there are considerable tensions between the US and Russia; I'm not the only person who has seen very alarming signs over the last few years in Russia's political system, and while there recently has been considerable protest there, there is still a paucity of viable alternative political figures to lead Russia to a healthier state. One such protester, Sergei Magnitsky, was a lawyer who unveiled widespread corruption in high levels of the Russian political establishment; he was arrested, held without trial, and mysteriously died after a little over a year.
Nations generally take an interest in the political doings of others, which is often a nervous affair as few nations have entirely clean hands; some nations are worse than others. American politicians took a particular interest in Magnitsky, foreign affairs being an easy unifying point for Dems and Repubs, and an easy way to get some props from human rights groups that focus on things like this. Recently a law was passed that would apply sanctions personally to a number of officials believed to be involved in the arrest and mistreatment of Magnitsky.
National pride and symbolism are generally the mark of an ill society; the United States has an unfortunate amount of this, but the less civilised parts of the world have significantly more; Russia saw the law as an insult, and has responded with an unusual gesture: it has proposed a ban on international adoptions by Americans of Russian children. That ban is currently making its way through the Duma.
The ban is symbolically named; there was a Russian boy by the name of Dima Yakovlev who was adopted by an American father, and in a moment of stupid and tragic negligence, his adoptive father here left him in a car for many hours and he died. The adoptive father was cleared of any legal wrongdoing, leaving the matter as a useful fact for the Russians to latch onto. I have little opinion on Dima's case; accidents do occasionally happen in childrearing, and hopefully as infrequently as possible, occasionally these are fatal. With enough people, even the reasonable will sometimes make mistakes of this sort, although I don't know whether the father was an idiot, made an understandable mistake, or something else.
It's worth noting as well that most American adoptions of Russian children, at least as suggested by the fact-checkers I've read, are of undesirables; healthy children primarily are adopted in Russia, leaving those with unfortunate diseases (such as AIDS) and various forms of retardation and other mental defects. The reason this is relevant is that the Russian bill likely shifts the fate of such children from a hopefully-caring family in the United States to a life in state institutions in Russia; Russia doesn't export children that it could find homes for internally (which makes sense, given the language barrier, logistics, and other factors).
Still, as a symbol, Russia will have been shown not to be weak in defending its honour, which is probably what counts to many of the Russian public. Just as we have honour-obsessed people here who believe in manifest destiny and the shining shitty on the hill and the flag and all that rubbish, they have their counterpart, and it remains hard to pressure another nation from the outside.
Which is not to say that I disapprove of the US pressure over Magnitsky; we hopefully are not uncaring businessmen like China who would deal with butchers of humanity for monetary reasons, nor undiscriminating hosts like Saudi Arabia who are always happy to spread their arms for those dictators like Idi Amin who have finally been given the boot from their dictators. We are willing to deal in blood, but I always hope only when the greater good for humanity as a whole is at stake. The US is not full of heroes; we know self-interest has clouded our judgement in the past, but this careful and complicated stance is what we should aspire to. Neither the idiocy of ultimate pacifism that enables violence and injustice, nor the immorality of self-maximising power plays should characterise us.