Steve,

I'm no expert on this line, but I've stumbled across a couple of things since your email arrived, and tried to pull them together. Based on the information you gave, I decided to start with a quick look in the Census for John and Myrtle and found this household in the Geary District of Roane County in 1930:

John W Justice (m) 33
Myrtle Justice (f) 26
Eugene Justice (m) 6
Ross Justice (m) 3 8/12
Elwanda Justice (f) 1 5/12

Now, knowing an approximate age for John, we can find this entry in Roane County birth records:
John Williams Justice b. 27 Nov 1897 in Geary District of Roane County
son of R.W. and Mary (Moss) Justice

A matching marriage record shows:
Robert W. Justice 23 from Roane county
Mary Ann Moss 16 born Kanawha county
married 1 May 1892 in Roane county

This gives us enough information to locate this birth record:
Robt. W. Justice b. 28 February 1868 in Roane county
son of Alexander and M.E. Justice

Death Certificates for both Robert and Mary can be found in the Vital Research Records section on the West Virginia Division of Culture and History web site at wvculture.org.

Robert's death certificate can be seen here.

Mary's death certificate can be viewed here.

Familysearch.org gives us a free look at this household from the 1880 Census in Geary District of Roane County:

A. Justice (m) 34
H.E. Justice (f) 36
J.W. Justice (m) 12
Robt. W. Justice (m) 11
M.J. Justice (f) 9
L.L. Justice (f) 7
S.A. Justice (m) 5
Mary Justice (f) 4
J.W. Justice (m) 2

Roane County marriage records show:
Alexander Justice 22 born in Kanawha county, son of Alexander & Margaret
Harriet E. Jones 16 born in Tyler county, daughter of Robert & Jane
married 7 August 1866

A check of Terry Cummings' Roane County Blue and Grey shows that Alexander and his father were both Confederate soldiers in the Civil War.

Alexander Justice, Sr. was a Private in Co E of the 22 VA Infantry CSA
Alexander Justice, Jr. was a Corporal in Co G of the 19 VA Cavalry CSA

Don Norman has a file on this Justice line which can be found here.

I did notice a couple of books in the family history section of the RCHS's Genealogy room at the Roane County Library in Spencer, but I did not have the opportunity to investigate them.

I hope this is enough to give you a good start. Good luck with your search!
-Richard