Their last angle didn't fly with the courts, so they're trying a new tack - claiming Pfizer's patent should be invalid because the drugmaker didn't provide enough information about Viagra's active ingredient. According to Teva, Pfizer's application gave a laundry list of ingredients, but didn't single out sildenafil as the active compound. Little late to be bringing that up now, don't you think?
That's maybe not as extreme as Teva's previous claim that Pfizer committed fraud when it filed it's initial patent for Viagra. Apparently the court doesn't find it frivolous, since it agreed to hear the case - but maybe the court is planning to make Teva an example of what not to do..
On the other hand, if they win, the payoff for Teva could be huge - they could sue for years of lost sales.