Can you trade for your friend with their account with their permission?

Am I legally able to enter/exit trades for a friend on their account that they gave me permission and access to use, while they also direct me on which trades to enter/exit?

Basically I would not be making any of the decisions, but trading for them since they are not able to access their account at work, but they can view charts.

Couldn’t find any laws on this topic.

Thanks.