What do I do if they charged me with Possession-Delivery/Manufacture when my friend was smoking his own weed?

I was walking down the street with my friend and we were smoking a joint. The police rolled up a few minutes after. They searched my friend. The person found a pipe and a grinder full of marijuana. They found nothing but cigarettes on me. When officer 1 asked to search my bag, I said no, not without a warrant and he said okay. Officer 2 came up to me and asked why he couldn't search my bag. I said because I don’t consent to searches. He then said that he smelled marijuana and they hand cuffed me and searched my bag. They found 9 grams of marijuana and a digital scale. The only reason I had a scale was to prevent myself from getting ripped off and to judge how much I smoke at a time. Are they allowed to charge me with this?