If my partner commits a crime, am I also liable?

Under the rules of accomplice liability, or the rules governing conspiracies, it may be possible. However, it would depend if there was an act committed in furtherance of the illegal conduct by you, and more information would be necessary to gauge whether or not you could be held liable. For example, if you were merely a partner with another individual, and that individual committed an offense entirely separate in time and place from the partnership and from you, then you likely would not be liable. If, however, you drove your partner to commit he offense, you likely would be liable.