Is there a alcohol test that can detect back 7 days?

There are blood tests that can detect alcohol use that occurred even longer than 7 days. Usually only larger amounts or prolonged drinking however. These tests are not detecting alcohol (ethanol) rather physiological changes that result from drinking.

Phosphatidylethanol (PeTH) is an example, detectable at 2 weeks post-consumption. There are several others as well. (Ex. See Hartmann, et al, 2007)

These Tests Do Not Detect Alsohol, But The Metabolites Left Over From The Metabolism Of Alcohol By The Liver. 7 Days? Yes They Can, Sometimes Longer Than 7 Days. Don't Rish It. If You Are On Parole Or Probation, Obey The Rules, Then When You Time Is Up, Drink If You Want To. But Don''t Drive At The Same Time!