The US Government Printing Office's Federal Digital System (FDsys) website provides access to many federal court opinions. This collection started as a small pilot project back in 2011; when it launched, it included only three courts, but it has grown substantially in the last few years. The coverage varies, but currently opinions may be included back to 2004 for 10 of the US Courts of Appeals (including the 5th Circuit), 26 US District Courts (including the Northern District of Texas), and 38 US Bankruptcy Courts (including the Southern District of Texas).
You can choose to browse for opinions by court, or you can use the simple search, advanced search, or retrieve by citation features. After you find the opinion you are interested in, FDsys will also allow you to view the document in context, which provides you with information about and links to other associated opinions for the same case. For more information about searching in FDsys, view the FDsys tutorials or FDsys Help page.