Hi,
I am a resident alien living in US from the past 8 years.
Filing Status: married & filing jointly

Last year in 2007 my mother-in-law and father-in-law came to visit us in USA. They came to USA on April 23, 2007 and left for India on September 10, 2007 (approx 4.5 months). My mother-in-law after going for a month to India came back on October 14, 2007 and will stay with us till march 2008. I know from previous questions that since she stayed with us in USA for more than 6 months in 2007 I can claim My mother-in-law as dependent in my 2007 tax return.
My question is related to my father in law, since he stayed with us for less than 6 months can I still claim him as dependent ?

Thanks for your help.

Negative.

The dependent MUST be considered to be a resident for tax purposes. Your father-in-law failed to meet the 183-day Substantial Presence Test, so he cannot be claimed as a dependent.

Further, your mother-in-law may not be eligible as well. First, if she earned more than $3,400 in income in her name from ANY world-wide source, she too becomes ineligible to be claimed as your dependent. Second, you must have provided more tha HALF of her total support for the entire year of 2007; this is questionable given that she spent almost five months in India.

If you meet BOTH of these requirements, you CAN claim her as a dependent; otherwise, no.

To claim your parents under Qualifying Relative it is not required that your parents live with you. They can be in a foreign country for whole year. Main requirements are:
1. You cannot claim a person as a dependent unless that person is a U.S. citizen, U.S. resident alien, U.S. national, or a resident of Canada or Mexico, for some part of the year.
2. You provided more than half of their support
3. Their income is less than $3,400.

I don't think that a person on tourist visa will qualify to be resident on the basis of SPT. Just like F1 (5 years) and J1 (2 years) periods are exempt form residency status, the tourist visa period should also be exempt.
Once again, about tourist visa period is exempt form SPT, I am not sure. I am looking for relevant IRS clause.

The TTE and I have argued this point at some length, and have agreed that PARENTS of foreign nationals who are resident aliens MUST meet residency critieria to be consideed dependent.

For foreign nationals, the residency criteria is the 183-day Substantial Presence Test.