Justinian wanted to restore the Roman Empire, but to do so he had to first pay off the Persians (Who the Romans had been fighting off and on for 200 years) and their allies the Avars (who lived in Modern Day Hungary). He paid both off, and then sent his army to Carthage and then Italy and then Southern Spain.
Justinian biggest problem was he was re-taking Roman lands, so the traditional way to pay for such conquest was NOT available, i.e. take over the country and sell the land to your supporters, kicking out the existing owners. The problem was the areas Justinian took had been Roman and the Romans had retained property rights in those areas. Thus Justinian could NOT use the sale of such land to pay the troops who took the land.
Worse, Justinian, inherited the traditional Roman Army of that time period, an army NOT up to the standards of Julius Caesar or the late Republic but still a MERCENARY army that expected to be paid (100 years later Emperor Heraclius would change this system, adopting what we call the "Feudal System", your pay for military service was your right to farm a piece of property, or have your serfs farm that property while you use the profits to maintain the arms and armor needed for you to fight in the army). The system Heraclius was similar to the system used during the time of the Punic War, when the Roman army was made up of its peasants who were UNPAID for their military service, but whose military service was part of their right to own and farm land under the Republic.
Anyway, such a change was not possible for Justinian, the people around him were the old Roman Elite which had grabbed all of the land of the Empire in the last day of the Republic and have had it ever since. Until the Persians took Egypt around 609 AD, the pressure from these elites prevented any reform of the Army, when the Persians took Egypt it freed the Emperor from having to listen to these large land owners, most of the land their owned was by then under foreign control. Greece, which had been the poorest part of the Empire had retain most of the rights of small land owners, Heraclius would merge his surviving troops with those peasants making the "Themes" of the Byzantine Army, that permitted him to defeat the Persians and then a generation later, fight off the Arabs during the Arab conquest (Through he lost Egypt for the final time, but Egypt had NOT been part of his Military Reforms, thus when Persia returned Egypt to the Romans, the Roman Elites went back and demanded their rent for all those years the Persians held Egypt, this turned off the Egyptian to Roman Rule and when the Arabs moved in, their embraced the Arabs as liberators, for the Arabs refused to accept Roman property rights and set up their own, which the peasants believed to be fairer to them then the old Roman Property Rights).
Anyway, back to the 500s and Justinian. The Feudal type system for the Roman Army was 100 years in the Future, Justinian had to use PAID Mercenaries. To pay such mercenaries he had to raise taxes, but not on his friends the Roman Elite, but anyone he could marginalized. This included the few Pagans that survived, Heretical Christians, and anyone he could marginalize among the Roman Elite (this included charges of "Stealing inheritances" and other similar accusations.
I have complete faith Justinian used the charge of homosexuality as an excuse to take someone's wealth. It was unimportant if the charge was true or not, but it was a good charge to take over the wealth of someone NOT in the Emperor's favor. Justinian would also charge such people with any natural disaster that occur (including the First big Plague of the Middle ages, Justinian Plague).
Now, having bashed Justinian, he had his good points, for example in his Justinian Code he permitted marriages to be valid on love alone, prior to Justinian a dowry was needed to make a Marriage valid, but Justinian changed that. This is believed to be do to the influence of his wife Theodora, who herself had been a poor actress when Justinian first saw her, and later married her. Theodora was loyal to Justinian, and provided him support, for example during the Nika Riots, when the mob of Constantinople had proclaimed another person Emperor and Justinian was planning to escape, Theodora is reported to have said, the the Imperial Purple Robe worn by the Emperor and her as his consort can also be a "fine burial shroud". This provided Justinian enough support for him to stay in Constantinople until his troops could arrive and re-take the city from the mob.
For more on the Nika Riots:
http://en.wikipedia.org/wiki/Nika_riotsJustinian (483-565 AD):
http://en.wikipedia.org/wiki/Justinian_ITheodora (500-548 AD):
http://en.wikipedia.org/wiki/Theodora_(6th_century)
Emperor Heraclius (575-641 AD):
http://en.wikipedia.org/wiki/HeracliusJustinian Code, Justinian Greatest Achievement:
http://en.wikipedia.org/wiki/Corpus_Juris_CivilisAs a whole, Justinian was considered a Good Emperor, his biggest problem was his failure to understand he needed to do land reform, but that was something that had been needed since 100 BC, and no Roman had ever tried it since the Gracchi around 133-123 BC.
More on the Gracchi:
http://en.wikipedia.org/wiki/GracchiThe chief reason Justinian went into Carthage and later Italy was to undo land reforms the Vandals and the Ostro-Goths had started. Both Germanic Tribes realized they more in common with the Roman Peasants then the Roman Elite and thus were more then willing to take land from the Roman Elite and give it to the Roman Peasants. This made both sets of Germanic Barbarian popular with the poor of North Africa and Italy, and equally unpopular with the Roman Elite around Justinian. Thus Justinian attacked both Countries and bankrupt the Eastern Roman Empire to regain these lands for the Roman Elite. This was Justinian's biggest failure, his refusal to understand that to retake Former Roman Lands he had to give the land taken NOT to his Fellow Roman Elite but to the Roman Peasants.
The Germanic invaders as a rule were also slow to do this land reform, but as things went from bad to worse, even the Germanic Tribes that had OPPOSED such land reforms (The Franks for example) adopted it. This require the elimination of every Roman Elite in Western Europe, but no one was willing to do that till the ninth Century. In the Ninth Century, facing Arabs attacks from North Africa, Vikings from the North, and Magyars from Hungary, Western Europe adopted a variation of Heraclius Themes to make Medieval Feudalism. This included giving the peasants RIGHTS to their land, the same peasants had to live on the land and had duties (and these duties were known to both peasants and masters) to their "Masters", but were free for any other purpose. Thus amounted to the land reforms that Western Europe had needed since 150 BC and lead to Europe becoming so strong that it repelled all three of its Invaders of the Ninth Century AND by the 1100s was strong enough to launch the Crusades.
This is a Classic Example of a Note made by Adam Smith, Nothing that benefits the common man, harms a country, it is the "Rights" of the elite that cause harm to nations.