The property left my father was litigated and final court order was issued after 10 years, what is to be considered as date of inheritance for purposes of calculating taxes?

10 years? What country?

The year of the death of your father.

What taxes? There is no federal tax on inheritances.

But there MAY be estate taxes, or inheritance taxes at the state level.

And there will likely be capital gains taxes due if the property is sold.

To the OP - if this is in the US, the basis for capital gains calculations when the heir sells the property is usually the date of death of the decedant. However, the executor of the estate may have decided to use an alternate valuation date when he originally valued the estate - so ask the executor what date he used. If unknown, then use the date of death.