Drug Courts Improvement Act of 2005 - Amends the Omnibus Crime Control and Safe Streets Act of 1968 to authorize grants for a drug court only if the court has mandatory periodic testing. Directs the Attorney General to specify testing standards, which: (1) shall ensure that each participant is tested for every controlled substance or addictive substance that the participant has been known to abuse and for every other commonly used controlled or addictive substance; (2) shall ensure that the testing is as accurate as practicable; and (3) may specify the regularity of the testing.
Allows grant amounts to be used: (1) for a drug court that imposes immediate and dramatic punitive sanctions, therapeutic measures, or both, whenever a participant fails a drug test; and (2) by a drug court to carry out programs under which the court holds hearings in public places such as schools. Lists examples of such sanctions and measures, ranging from incarceration to increased drug screening requirements, increased counseling, electronic monitoring, and public apology.