I need to know if I as a defendant can have the so called victims tested for drugs before they testify?

Hello my husband is accused of shooting @ a 14 year old & 5 guys over the age of 20 in the woods on New Year's. The other people had a gun & pulled it on my husband & his friends & a fight did ensue. The 14 yrs.old is a known drug user & her mother cares less what she does. My husband & our friends came home & everyone went there way. The incident was to have taken place @ 3 am, it wasn't reported until 3pm the next day. MY husband & I came home from me riding my 1st horse & r neighbor came over when we got home & told us that the police was looking for him, so him & r neighbor walked down the street to the other street where the cops were & my husband told them his name & he had heard that they were looking for him. No sooner did he say his name they had him cuffed & shoved into the car. My husband was on probation, he was getting ready to get off early per his probation officer who had told him to get the paperwork she would approve it. He didn't find out till 4 am the next morning as to what he was being arrested for. Everyone of the so called victims have records as well the only difference is that my husband had been turning it around. We are active members of our church, grandparents, & he worked at a horse rescue well not worked cause he didn't get paid he just loved doing it. I need to know if we are able to have our lawyer to have these people drug tested b4 the testify. I was told that two of the guys keep pea on them for their jobs cause they can be tested at anytime. I also have pictures of them buying drugs from a known drug house, I turned them into the police but they weren't able to do anything to them. I know that they any of them are not going to be clean. Can anyone tell me how I go about this? I also need to know how do I go about getting something done cause they the police arrested my husband on a decision based Solly on his past record it is a bias prejudice I believe that is what I was told? My husband & I have not always walked the straight line but he didn't do this!!! I am disabled & he took care of me & helped pay the bills. I have now loss our home due to this injustice & this people are walking around steadily getting into trouble. We have several people from our church that will stand up for us & to say how we have come a long way. If anyone could please give me any info that would be helpful I would really appreciate it.