I've been expecting this question ever since I got my flair. Luckily, I came prepared. This might be a long one.

So this is obviously a very complex topic since, like many modern famines, the Ethiopian famine of 1983-1985 was a combination of natural and anthropogenic factors that led to the death of 400 000+ people. I'll try to discuss both the causes and the response to the crisis which will help us deduce the government's responsibility.

Note: I'm assuming you already know the basic geopolitical situation but a quick recap: Since 1974, Ethiopia was under the rule of a marxist-leninist military junta known as the Derg led by the autocratic Mengistu Haile Mariam. In the north of the country two other marxist rebels groups: The Eritrean People's Liberation Front(EPLF) and the Tigray People's Liberation Front(TPLF) waged a long war against the regime until it was overthrown in 1991.

Agricultural situation and Vulnerability to famine

Agriculturalists in Ethiopia are represented by the peasantry who account for the vast majority of the nation's population. Most of them are subsistence farmers who maintain themselves by growing crops or rearing livestock. Farmers are dependent on 2 rainy seasons: the belg(February-May) and Meher(June to September). The latter is the main one during which long maturing crops are planted and are harvested in November. However, this is often insufficient to sustain families in many areas of the country. Nutritional surveys carried out even before the 1972-4 famines revealed very low levels of calorie intake,vitamin deficiencies and the presense of goiter(caused by low iodine uptake) among the peasants of Tigray,Eritrea and Hararre. Therefore, for most of the year, the vast majority of families are dependent on the market which allowed food to be funneled from surplus producing areas to regions where there was high demand. The existence of a large market network was in a sense a barrier to large increases in grain price. When the price rose in one area, traders would buy food in markets where it could be bought more cheaply, and move it to deficit areas— both supplying food to the area and so bringing the price down, and providing a market for farmers in surplus areas. This vital role of the markets will be important when we start discussing the effects of their destruction.

The RRC

The Relief and Rehabilitation Commission was established by the Derg on August 29, 1974, days before the Emperor was deposed. It's job was to 1)provide relief to the starving people suffering from the Wollo(or more appropriately the 1973-75) famine and 2) rehabilitate the effected population and prevent similar famines from striking the nation. Interestingly, ignoring the Wollo famine was one of the major accusations made against Emperor Haile Selassie when justifying his overthrow. In fact, the day before he was deposed, the Derg aired to the public an edited version of Jonathan Dimbleby's film on the famine in which footage of starving peasants was juxtaposed with images of the Emperor's lavish lifestyle. We'll soon see the new government would turn out to be not very different. But, initially, it placed a major emphasis on famine, using it to discredit the old regime and win over the population. Hence,the RRC was created. By law the RRC had the power to ask for and receive assistance from domestic and foreign sources. It set up an early warning system in 1976 to inform the government as well as donor agencies of impending food shortages. The organization, as you'll see below has quote an important place in the history of the 1983-85 famine.

For the rest of the answer, I will be going through each factor that contributed to the famine one by one. Here goes nothing!

The natural causes

The natural element that brought about the starvation in Ethiopia-drought is actually quite a controversial issue as during the 80s, various sources would put varying degrees of emphasis on its role in creating the famine. After the downfall of the regime, Alex de Waal's works argued that the famine in northern Ethiopia began BEFORE the drought set in. In early 1983, the government's relief agency- RRC, the TPLF's relief agency-REST as well as several foreign groups started making warnings about an upcoming famine and began calling for aid. These alarms began because the relief shelters in Korem and Ibnat(central Gonder) were being flooded with increasingly more malnourished people. According to Dawit Walde Giorgis, head of the RRC, hundreds were dying each day by August 1983. Although, the RRC attributed it to drought,this "flow of destitute migrants was in fact a direct result of the war". The main issue is that the harvest failures between 1980-1983 were not huge enough to explain such high deaths in early 1983. We don't have any figures for food production in Tigray, but take a look at the FAO's data on the national total(Note: 1974-1976=100):

Year	total	per head
1977	99	95
1978	110	104
1979	122	113
1980	117	106
1981	115	102
1982	127	110
1983	118	99
1984	110	90

As you can see, we wouldn't see a major drop in national production till 1984, in fact 1982 was actually an above average year. According to the RRC, regional food availability in Tigray, Wollo and Gondar was normal in 1980-81, with surplus reported in eastern Tigray,northern and southern Wollo and central and northern Gondar in 81. In 1982, eastern Gondar suffered drought but the above mentioned surplus areas were not affected as much. In early 1982, the situation in Tigray was described by the RRC as "encouraging" but a few months later it was described as "poor". This change was based not on any new surveys, but on the sharp increase in grain price in Meqelle. However, later we'll see that this rise was largely due to the restrictions on the rural-urban trade imposed by the government. RRC's April 1983 report(this is months before the meher season) was much more alarming. A famine had already began but the droughts hadn't set in yet. The first signs of major crop failure were seen in the main meher season of 1983 but even this was confined to Tigray and parts of Wollo(the situation in Gondar actually improved). Almost universal drought set in 1984, which first saw the failure of the belg rains and then the failure of the meher rains. This resulted in a catastrophic drop in food production in Tigray,Wollo and Gondar. We have no figures for Tigray, but in Wollo production dropped to 28% of 1983 levels. In fact, contrary to the government's claim of "an ever worsening drought between 1982-84", 1984 was first year that saw a major drought, yet, as mentioned above, the famine began a year earlier. This is best visualized by looking at rainfall data from Kobo in northern Wollo(which was close to the epicenter of the famine):

Year	Belg	Meher
1977	268	460
1978	117	352
1979	233	497
1980	118	499
1981	NA	646
1982	168	362
1983	250	150
1984	19	51
1985	214	243
1986	174	450
1987	331	233

(Note: Rainfall data is actually difficult to obtain as they were concealed by the government. These figures, measured in millimeters, is taken from Evil Days which cites Alemneh Dejene, Environment, Famine, and Politics in Ethiopia: A View from the Village, Boulder, Co., 1990, p. 84.) This confirms that droughts began in late 1983(although the belg rains were normal) and complete failure of the rains wasn't seen till 1984. By the time these droughts began, famine had already set in. Another factor to keep in mind is that the 1982-3 droughts in Tigray were largely localized to its eastern regions, but it was southern Tigray that was worst hit by the famine.