My house was raided by police after they were tip of about someone that is supposedly selling drugs this person does not live at my house. While they raided my home they discovered some cigerettes that duty had not been paid. My son who does live with me said they were his so they arrested him,after 4hrs they realeased him with no charge. My question is was it OK for them to drug test him also was it right for them to return 13 days later and take more dna from him which they did in my living room

Are you in the UK as I see you use the Term Solicitor?

... my question is was it OK for them to drug test him also was it right for them to return 13 days later and take more dna from him which they did in my living room[?]

As suggested by Smoothy, you appear to be in the UK. While the law concerning search and seizure is not quite the same in the UK as in the US, there are similar features. So, assuming they did not have a warrant, what you describe suggests that the police may have violated the law. The main issue I see, however, is that it doesn't appear that he can prove money damages. I suggest that he contact a solicitor to find out if he has a case.

Did they ask him for the test and he say "OK" and just do it.

Or did they ask to do the test and he say "NO" and they held him down and took the test against his will

Big difference.

They can always ask, if he just agree's, there is nothing wrong.