The 29-year-old took a dietary supplement when playing for Wellington last season and was tested at a Ford Trophy match against Northern Districts on March 24.
He returned a positive test for 1-Phenylbutan-2-amine (PBA) and N, alpha-diethyl-benzeneethanamine (DEBEA), both of which are banned in competition.
The mandatory penalty for this violation is two years' suspension but Ryder was handed a lighter sentence because he was able to establish how the prohibited substances got in his system and that the taking of the prohibited substance was not intended to enhance his sport performance.
He is banned until October 19 and the domestic cricket season normally begins towards the end of October.
Ryder admitted the violation and stated he had been using a dietary supplement in order to lose weight and had taken two capsules five days before being tested. The supplement didn't list any prohibited substances on its label.
After testing positive, Ryder engaged a forensic analyst to test the product and she confirmed the presence of prohibited substances in the product and the analytical findings were consistent with his evidence of when he took the capsules. The tribunal was satisfied that the source of Mr Ryder's positive test was the supplement.
Ryder took the supplement on the advice of a friend who had success losing weight using it. He made some enquiries on his own about the product, including internet searches and asking the strength and conditioning specialist he worked with about it, who also did some searches. Ryder concluded it didn't contain any prohibited substances and got his manager to order it.
When he received the product he noticed it contained a warning on its label stating it may contain ingredients banned by certain organisations. He made internet searches on two of the ingredients but didn't contact Drug Free Sport to check about the product even though the product contained a warning.
As a professional cricketer, he had been subject to anti-doping education, including attending Drug Free Sport presentations during the previous season, and had received information about the need to be cautious about taking supplements. The failure to contact Drug Free Sport, having seen the warning on the label, is the most substantial factor of fault on the part of Ryder.
Ryder recently signed to play for Otago in a bid to relaunch his international career and his ban shouldn't affect his ability to do that. The domestic cricket season normally begins towards the end of October.
He last played for New Zealand in February 2012 before making himself unavailable after a "deeply stressful and emotional time'' in the spotlight but it one of the most damaging players in world cricket.
He averages 40.93 in his 18 tests, with a high score of 201 against India in 2009, and 34.37 in 39 one-day internationals.
Ryder's chequered career has earned him a cult following, as well as plenty of opprobrium since his international debut in 2008.
He was attacked outside a Christchurch bar in March, when he suffered a head injury and spent two days in an induced coma in Christchurch Hospital.
Two men were charged with assaulting Ryder - a 20-year-old carpet layer pleaded guilty to one charge of assault and a 37-year-old builder has elected trial by jury, which has yet to be heard.
