Here's another piece on this case.
The Texas and US Solicitors General raised what would seem to be a pretty persuasive technical point against the plaintiffs:
Emphasis mine.
The apportionment clause of the 14th Amendment would appear to require the collection of CVAP data. The Census used to collect citizen data, and until the 2000 census did so as part of the actual census. Presumably, the census bureau thought that the ACS was as good as the census sample, and better because it was continuing.
The Federal Government as part of its enforcement of the 14th and 15th amendments requires use of CVAP.
Can the USDOJ require racial data to be included with Section 5 submissions, since the census is not required by the Constitution to collect racial information?
Legislative and congressional districts do not take into account persons living overseas, and the federal government doesn't bother to try for persons not working for the government.
The Texas Solicitor General did not say the ACS data was not reliable enough to use for redistricting.