Are there communities where yibum is done? If so, doesn't the bigamy situation conflict with the law fo the land? Or, since yibum is really a continuation of the former marriage there is not ketuba or civil certificate? In which case yibum would create a bigamous situation that's under the radar as far as the civil laws are concerned?

If the brother is already married then he is not allowed to do yibum in the State of Yisrael. Over the centuries, I doubt if married men took the opportunity to do yibum but any of the brothers can do it. In any event, the yevama is sort of half married to the brother and the Bet Din will not allow her to marry again until he does chalitza.
As I said, the last yibumim I am aware of were Yeminite jews in Rechovot in 1950's.

Biblical accounts
The torah was not given in a vacuum. Many of the laws existed in a different form before the giving of the torah, e.g. the sentence says that one should not convict by one witness but by two or three witnesses in capital cases. Presumably the bnei yisrael were familiar with the one witness situation. Yehuda does yibum for his daughter-in-law as all the brothers were deceased. There is no such obligation for yibum after matan torah. Also Tamar is supposed to be burned. The torah calls for stoning unless she is daughter of a cohen. The torah temimah feels the midrashic answer raises more problems than it solves and suggest the text is talking about branding (Scarlet Letter).

The chalitzah described in Ruth also does not seem according to the halacha. The goel (the redeemer) is not a brother and has no obligation to do yibum. Apparently it had to do with land laws at the time. From the text it does not appear that Boaz does yibum but is purchasing Ruth along with the former husbands estate.

Aryeh Shore

quote:

Originally posted by laurence shore:
The way to test for right footness is to ask the man to kick the wall. If he uses his right foot he is right footed.

I can kick the wall better with my right foot, but I write with my left hand, better than with my right one. It was pakened for me, that I'm a lefty and i put tefillin on my right hand. So the test that you proposed, is not a 100% definite answer.

Don't understand your problem. Your are right footed and left handed. The nervous system crosses over so if you are right brained your are left handed but not the all nerves necessarilly crossover. The second test is to ask someone to step on a chair. As mentioned, especially in marching one can be easily be conditioned to lead with the left foot. It is very hard to get a righthanded person to shoot or eat left handed so I guess it is more hard wired.

Aryeh Shore

What I'm saying is that, the test is not 100% accurate. It was a Rebbi of mine who was giving a class around the time before I was Bar Mitzvah, and he had asked everyone to line up against the wall and kick it. I had kicked it with my right foot. He said that the test is good for if one is ambidextrous.

If one writes with his left hand does that make him a lefty for Chalitzah too?

That is not a good test is apparent from the discussion on marching with the left foot. The halachic solutions for amdextrious or even left footed people (since it is not clear if it is the right foot of all men or the individual)go something like doing the right foot and then the left foot or both together. It was these solutions that R.Weiss rejected as being too complicated for the average person off the street.
I am unaware of any science literature on ambidextrous and handiness. Neurophysiologists haven't express much interest in defining the problem although numberous inconclusive genetic studies have been done.

Aryeh Shore