Not much to interpret the language in the law in question is plain. The Federal Records Act (started in 1950 and amended many times since) requires all federal employees to keep any records pertaining to their official duties. Furthermore is stipulates that each agency provide general and specific requirements regarding how records should be created and maintained at that agency. As such, the IRS has such a requirement/policy which I link before, but I'll link again for the truly useless in here.
http://www.irs.gov/irm/part1/irm_01-010-003.html
That document requires there to be a backup printout. This didn't happen and was a breach of the Federal Records Act requiring the IRS to maintain its records according to policy. Also, one might say that the server is the backup in most cases. Although that may be the case, and was likely the case here. The fact that no effort was taken to recover said backups when a problem occurred with original records is also a violation of the law seeing is how there was effectively no backup at that point, which again is required under their own policy which in turn is mandated by the Federal Records Act