Michelle Boardman at the Volokh Conspiracy raises an interesting question concerning the war on drugs - should the federal government be able to withhold federal funding from someone (or thing) that criticize federal drug laws (or, I presume, what ever the policy complaint of the moment is)
She's leaving the first amendment discussion to Eugene, but feels that the government shouldn't be able to shield itself from criticism in this way. While I want to agree with Michelle at a gut level, I can't help but feel that the government shouldn't be forced to subsidize criticism of its policies. The federal government is under no obligation to fund METRO (though of course, speaking as someone living inside the beltway, its in everyone's best interest that it does) and METRO is under no obligation to accept funding. Similarly, I am under no obligation to ride METRO, and if I do, am under no obligation to view the advertisements. However, if the government does decide to fund some activities and not others, I think its perfectly acceptable that it impose limitations on the use of those funds. A prohibition on certain types of advertising seems perfectly reasonable.
I know some people are going to argue that the analysis can't be that simple because of the special position the government occupies. True, but in this case, the government is acting as a market participant and has decided that its easier and cheaper to pay METRO to operate the trains than it would be if the federal government operated them (I don't necessarily buy this, especially in regards to METRO, but that's the argument nonetheless). As a market participant, the Government ought to have the right to dictate how and in which way its contractors perform. Certainly, if the Federal Government ran METRO outright, it could be more discriminating in the advertising it accepted. If that's the case, I would argue that it can impose those same conditions on its contractors.
Still, one lingering concern I have is that the prohibition is too narrow and therefore may be unfairly restrictive ie: why is some criticism allowed but others not (and can pro drug control organizations still run ads?).
While I think the perfect solution is to institute either a blanket prohibition on issue advocacy advertisement (or all advertisement) or have no prohibition at all, I have a hard time imposing restrictions on the government's actions as a marketplace participant that I wouldn't impose on a private individuals acting in the same manner.