The Laws of Medinas Yisrael

The Laws of Medinas Yisrael:

Daf Hashavua
Bava Basra 54b

והאמר שמואל דינא דמלכותא דינא    

There is a Machlokes Rishonim if Dina D'malchusa is 
applicable in a Jewish Malchus.

According to the רמב"ם & רשב"ם Dina D'malchusa is applicable
even in Eretz Yisroel with a Jewish Government.

According to the ר"ן the land belongs to the Shevatim
and all of Bnei Yisroel, therefore the Malchus has no power 
of Dina D'malchusa.

 Laws that the populace  accepted amongst themselves 
and are willing to pay taxes because it benefits the inhabitants 
even the ר"ן will agree Dina D'malchusa applies in a Jewish Malchus."

Today with the State of Israel whose government is non-Frum,
according to,

a) Harav E. Henkin & Harav Ovadya Yosef zt"l, all the laws 
(not opposing Torah) must be followed because of D.D.

b) Harav Y.S. Elyashiv zt"l, held it is a Safek*

c) The Chazon Ish  held  there is no Dina D'malchusa in Medinas Yisroel.

Most Poskim would probably agree,
1) D.D. is applicable on traffic laws and building codes etc.
2) Those who benefit from the social programs may not
cheat on their taxes.

*The אבני מילואים אבהע"ז כ"ח & חת"ס יו"ד ב' שי"ד
both argue on the בית שמואל כ"ח:ג  and hold
D.D. is דאורייתא , therefore might be a
ספק דאורייתא