However, prosecutors are allowed to seek testimony from up to five other women who have said Cosby also drugged and assaulted them in previous incidents. The prosecution argues that these "prior bad acts" witnesses show that Cosby's behavior shows a pattern of misconduct and he did not make a one-time mistake in his actions toward Constand.

https://www.cnn.com/2018/04/12/us/bill-cosby-trial-janice-dickinson/index.html

Constand takes the stand today I think