An Italian prosecutor stood in a Bologna court on Wednesday and asked that manslaughter charges against Williams personnel be dropped because too much time had elapsed.
But the accused are seeking an explicit vote of not guilty, rather than a mere dropped case.
"In (motor racing) you have to accept that there is a risk factor," their lawyer, Luigi Stortoni, insisted in Italy.
Brazil's Senna, 34 - one of the greatest F1 drivers - died after he crashed oddly at Imola's Tamburello bend in 1994.
A case against F1 bosses, including Adrian Newey and Patrick Head, resulted in acquittal in 1997 and (on appeal) 1999, but was reopened in 2003.
Judges will rule on the latest development on May 27. -GMM