The lawyer representing Lidle’s widow told the Associated Press  that today’s verdict for Cirrus was a foregone conclusion once the judge decided to keep out certain key evidence.

. . .the jury result was predictable because the judge refused to allow jurors to hear that the company revised its manufacturing process after the crash to prevent the flight controls from getting jammed. She also had ruled that they could not hear that a flight instructor had a lockup of flight controls and almost crashed in a similar plane.

Should the judge have allowed the evidence in?

Generally, the fact that a manufacturer has “fixed” what the plaintiffs consider to be a defect is not admissible to show that the manufacturer was negligent. Otherwise, manufCirrus Side Stick Controlleracturers might be reluctant to remedy problems after an accident. But there is an exception to the exclusionary rule under the Federal Rules of Evidence. The jury may hear of "subsequent remedial measures" where that evidence proves that the manufacturer could have easily designed the product in a safer way. 

When, after an injury or harm allegedly caused by an event, measures are taken that, if taken previously, would have made the injury or harm less likely to occur, evidence of the subsequent measures is not admissible to prove negligence, culpable conduct, a defect in a product, a defect in a product’s design, or a need for a warning or instruction. This rule does not require the exclusion of evidence of subsequent measures when offered for another purpose, such as proving ownership, control, or feasibility of precautionary measures, if controverted, or impeachment.  

The exception might have applied to allow into evidence Cirrus’ "fix" for the aileron control system, but only if Cirrus argued that there was no feasible safer alternative design for the system.  We don’t know from the news reports whether Cirrus made that argument. But it’s unlikely Cirrus would have commited such a strategic blunder. 

What about the evidence of another Cirrus aircraft whose controls locked up? Usually, evidence of “other similar incidents” is very important to a jury.  If a design is defective, one might expect that others would have experienced the same problem.  But judges are wary of admitting evidence of "other similar incidents." Proving what happened in other cases can take up considerable court time, creating a "trial within a trial."