Excommunication, Exclusion from the Eucharist, Abortion Legislation and Canon Law

Dr Edward Peter's concise post is essential reading for anyone who wants to be informed about the various canonical issues that surround politicians, abortion and excommunication.
Very importantly he highlights the distinction between excommunication and being in a state of grave sin that excludes one from receiving Holy Communion:

Here's the Shorter Version: First, Canon 916. There are lots of mortal sins out there; if you commit any one of them, you're not supposed to go to Communion. It's your obligation to stay away. Next, Canon 915. Some mortal sins are committed under circumstances that, if the Church finds out about them, not only are you supposed to the stay away from Communion, but the Church is supposed to turn you away if you try to receive. Finally, Canon 1331. A few mortal sins are serious crimes under canon law; if you commit one of those, you can suffer the penalty of excommunication, and one of the consequences of excommunication is, you can't go to Communion.

He also draws the following conclusion that gels pretty well with my reading of the
1983 Code:

(3) Under the current Code, no one can be excommunicated (automatically or otherwise) for pro-abortion legislative activity. Such activity is nevertheless potentially punishable under other canons (e.g., Canon 1369) albeit not with excommunication. Moreover, particular legislation, personal precept, or contempt for lesser penalties, might make pro-abortion legislators liable to excommunication in the future. To my knowledge, though, none of these options is being pursued.

Please note... whilst the 1983 Code does not give excommunication is a possibility for pro-abortion legislative activity, this does not exclude legislation of this sort being introuduced by bishops at a local level.
Anyway, his entire post should be read to make the above clear.