It's analogous to the adultery of that Air Force pilot a few years back. USAF frankly doesn't care about adultery per se since it's not exactly a force threatening offense. However, the pilot disobeyed orders and lied to her superiors about the affair when it continued. Everyone focused on the adultery when that wasn't the crux of her court martial.
Red, there is no issue that the question should have been asked unless you are saying that we should prevent people from filing lawsuits when they feel they are wronged. Paula Jones thought she was wronged, though her case didn't reach the threshold of sexual harrassment, but the question was asked in the context of her lawsuit to establish a pattern of conduct. He certainly had one, and it was a legitimate question for that venue and topic. We pass laws regarding court testimony so that we can reasonably assure its accuracy. Simply because Clinton didn't agree with the suit doesn't give him license to lie about it and circumvent those laws.
This has nothing to do with the Republican party or partisan politics -- it's a FACT that he lied while testifying in a court of law. He's a lawyer also. There's no way to reconcile that falsehood, and while it might be fine for Joe Citizen who screws around on the job, it's not hunky dorey for the sitting President of the United States. So, he gets some head in the Oral Office -- who cares? He lies about it in court -- very big deal.
Sure, other Presidents may have cheated on their wives, but I doubt that any were as promiscuous as Clinton. How many have there been with him? Besides, the other Presidents weren't stupid enough to get caught and then lie about it.
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Simply because it is adopted in partisan politics does not make the underlying concept unsound. That line of reasoning is myopic.