This is a very difficult question to answer and would heavily depend on the specific time and location in which you were accused. The good news is, while an unknown number of suspected witches certainly found themselves the victims of vigilante justice, it is likely that you could expect to be granted some form of trial. I'll try to give a brief overview of how witch accusations were typically handled by courts in Western Europe. The vast majority of trials took place in secular courts using the inquisitorial procedure. Under this system, it was the responsibility of the presiding judge to gather evidence against the accused and interrogate them as necessary. However, a guilty verdict could only be returned on the basis of the sworn testimonies of two eye-witnesses, or a confession from the accused. Since eye-witnesses to witchcraft being performed were, quite predictably, lacking, most witch trials hinged on the extraction of a confession from the accused. This is where torture came in. In theory, there were strict controls on how and when torture could be used in the course of a trial, but in many jurisdictions these rules were modified, abused or disregarded in light of the 'exceptional' nature of the crime of witchcraft. These abuses were increasingly condemned throughout the 17th century, though unfortunately were not formally abolished until the 18th - after witch persecutions had more or less come to an end in most countries.

You would be, in theory at least, entitled to a lawyer. In practice, however, most people accused of witchcraft were too poor to afford legal counsel - and most lawyers were reluctant to defend accused witches. However, you were by no means 'doomed'. In Germany, courts were commonly required to approach universities for advice on how to proceed with witch trials before passing a verdict, and most jurisdictions had some form of appeals system. In 17th Century France, the appeals procedure was a mandatory feature of witch trials. Cases had to be brought before the regional parlement for assessment, leading to a relatively low conviction rate. In the Holy Roman Empire, cases of legal abuses could be brought before the highest court of appeals in the Empire, the Imperial Chamber Court, which from the 1620s onward severely denounced witch persecution and helped effect a change in attitudes toward witchcraft amongst lawyers and popular opinion.

In England, the situation was quite different. Here, procedure resembled something closer to what we would recognise as a trial in the modern West, with a lay jury determining the facts of the case. The majority of trials took place during the assize sessions - a centrally organised system in which two itinerant judges would be assigned to one of six 'circuits', presiding over trials across multiple counties. The relatively low conviction rates for witchcraft in England have been attributed, in part, to the presence of these highly educated, professional judges. Torture was not legally sanctioned in England, though suspects were often subject to mistreatment during pre-trial 'examinations', during which they might, for example, have their bodies pricked with pins in an attempt to find a 'witch's mark'. As mentioned, conviction rates for witchcraft remained relatively low in England, though there are outlying cases. The English Civil War and resulting breakdown of judicial authority gave rise to the notorious witch hunter Matthew Hopkins, whose extra-judicial activities throughout East Anglia lead to the executions of around 300 women between 1644-46.

Now, as for why this question is so complicated, the severity and intensity of witch trials varied massively even on a regional level. Take Spain, for example. In Navarre, where the Spanish Inquisition asserted near complete jurisdiction over witchcraft cases, it is likely that the accusation against you would come to nothing at all (the Inquisition had officially adopted a sceptical attitude toward witchcraft from 1610 onward). Meanwhile, in Catalonia, where the secular courts retained control over witch trials, witches continued to be tried - amounting to around forty-five executions between 1618-22. The situation in the fractured Holy Roman Empire was even more convoluted. A particularly zealous Prince Bishop or village committee might preside over the executions of hundreds of witches in a matter of months, while a neighbouring territory might see no executions whatsoever. Persecution of witches was sporadic, and a massive outbreak of hysteria could often be followed by a complete cessation of executions.

Typically, the most intense persecutions occurred in times and places where central authorities were unable to exert influence over proceedings. Hence, convictions under the advanced, centralised justice system of England or within the jurisdiction the powerful French monarchy were not as common as they were in the fragmented Holy Roman Empire. This is about as close as you can get to a generalised pattern of witch persecutions in Western Europe. It was once common to distinguish between the low level 'village witch' trials of England and the ruthless 'top-down' hunts of the Continent, but modern research does not bear this out. The vast majority of accusations across Western Europe began at the village level, fomented by neighbourly disputes and local circumstances, with the accused often living with a reputation for witchcraft for years, if not decades before a formal accusation was brought against them. Broad modern estimates place the total number of witch executions across Europe at somewhere between 35,000-50,000, resulting from approximately 75,000 trials. So in the most general sense, you were by no means 'doomed', but just how likely you were to be executed or even accused to begin with was hugely dependant on the local situation at the time.

Sources:

Wolfgang Behringer, Witches and Witch-Hunts

Robin Briggs, Witches and Neighbours

Richard M. Golden (ed), Encyclopedia of Witchcraft

Brian Levack, The Witch-Hunt in Early Modern Europe

James Sharpe, Instruments of Darkness

So I'm seeing a number of ways in which this question could be tackled. I should therefore give the proviso that witchcraft is not my speciality and that I cannot speak with authority on the various perspectives that this question invites. Nonetheless, witchcraft has its literature within the field of English Civil War studies and I can – to an extent – speak to that. The several questions seem to be:

• What are the prejudices against practitioners of witchcraft?
• What is the forum in which these would have been expressed?
• What is the likely punishment?
• Are there available defences? What are they?

I have split my reply somewhat artificially in order to respond to these questions individually.

Prejudices

Belief in magic is profound in seventeenth-century England. It is also widespread. Although certain counties, such as Northamptonshire and Kent, and socioeconomic classes, like the nonconformist peasantry, can be singled out for study, witchcraft was a punishable offence because even the government believed in witchcraft’s reality. James VI and I is the most famous example of a royal believer. He takes up his interest shortly before ascending to the throne and in 1597 writes Daemonologie. This famous tract makes the case that witchcraft is real, that it can be detected, and that it should be punished.

Witches are created by the interventions of the Devil. James gives some competing theories about how exactly the Devil enters the perceptions of his victims, but one is made susceptible by “great ignorance…, ioyned with an euill life, or else by… carelesnes and contempt of God”, whereupon the Devil visits his victim and brands his mark “upon some secreit place”. This mark brings “intollerable dolour [pain]”. The idea of witches being initiated by a coaxing voice persisted in the popular imagination; the mark of the Devil is used as incriminating evidence in every mass trial of the 1640s, and includes even flea-bites.

But the publication of this text, and its use during his ascendancy, is indicative of James’ desire to provide a single definition of witchcraft (“the trueth thereof”) that would bring the “doubting harts of many” not merely to belief, but to action. Consistently historians find the Jacobean and Caroline monarchs struggling to deal with religious nonconformity and an unregulated system of law enforcement which was built largely on the consent of local officials. James’ definition of witchcraft and its transformation into the 1604 witchcraft statute are in part attempts to triumph over these issues. Defining witchcraft contributed to the criminalising of what were contemporaneously considered superstitious practices. The strength of James’ rhetorical definition was its power to convince the hearts and minds of his local government that witchcraft was heinous and deserving of punishment. This is to say that James’ writing on witchcraft encouraged uniformity in significant ways, but it is not to argue that James acted solely out of political expediency. James earnest belief in witchcraft’s reality did not make him an outlier, and given his personal convictions he had good reason to bring the government into uniformity on this point.

Christopher Hill argues that the persecution of witches decreased in the seventeenth-century as Puritan individualism led people to blame themselves for the wrong-doings of the world. In the first place, it is almost impossible to measure informal accusations and persecution; in the second place, it would be difficult to pin a decline in anti-witchcraft practices on protestant self-flagellation. Nonetheless, we do know that prosecutions decrease from the period 1620-1640 and that this is generally considered to be the result of caution on the part of judges (/u/Nerbelwerzer gives concise expression to their organization in seventeenth-century England). By the time the English Civil War breaks out, witchcraft sat within a network of protestant and nonconformist doctrines. The witch became associated with the Catholic in the public consciousness, and those most fearful of it might come from radical religious backgrounds, such as the millenarianist movement which was to become one of the larger nonconformist sects in the 1650s.

The Dameonologie was significant, then, in the way that it set out a prejudicial idea of a witch which moulded the tests that would be used until the early eighteenth-century. Indeed, its demonological notions were bolstered by other tracts by William Perkins and Reginald Scot which, by virtue of their authors and their subject matter, enjoyed some popularity at the time. The Daemonologie failed in its attempt to create lasting uniformity in government and, for most of the seventeenth-century, trials over witchcraft were not common.

The Forum

The forum for witch trials in England is distinctive when set against trials on the Continent. Most of Europe would have operated under the civil law, where the anti-witchcraft statutes would have taken a different form. This means that the trial was in search of a different crime. Moreover, England used (and still uses) a jury system for criminal convictions. Legal representation would have been minimal compared to that which was available in other European countries. My two sources, to which I am entirely indebted for this section, are Baker’s authoritative An Introduction to English Legal History and the recent Marks of an Absolute Witch, which contains thorough answers to your question on every point.

Grand jurors would have been convened under the authority of a Justice of the Peace, one of the predominant local figures under the Jacobean and Caroline governments and those that James VI and I would have aimed to harmonise with the publication of Daemonologie. The jurors were disinterested parties who passed judgment with a quorum of 12. Despite the fact that these trials were criminal, there was no formal burden of proof and so grand jurors could work to different and competing standards of indictment. The indictment was compiled in Latin, to which the accused, often finding it incomprehensible, would plea guilty or not guilty. If the accused pleaded not guilty, they would be arraigned before a 12-man jury. The accused had no right to prepare against witnesses of the prosecution and would often be barraged by the prosecutor’s case.

In felony trials, there was a period in which the accused would be held in jail. Though torture was outlawed, confessions were frequently extracted from any accused who were put in a jail cell. My strongest a priori argument against torturing or harassing the accused during their detention would not be legal restrictions or technical incapacity, but the lack of motives on the jailers’ part. I will not stray into the likelihood of torture in detention - I will only say that the door to torture was open. Confession expedited proceedings since it was considered the ne plus ultra of criminal evidence throughout the seventeenth century. Confessions could also be extracted willingly, and Louise Jackson has argued quite persuasively that in a society where even the accused believed in and feared witchcraft, the uneducated might use it as a trope to describe their general moral shortcomings. Thus the uneducated might unwittingly hurt their own standing on court or, more likely, pave the way to their own immediate sentencing.

Cross-examination of witnesses was not part of the English legal process and so the evidence tended to mount on the prosecution’s side: famous witch-hunters like Matthew Hopkins would collect as many testimonies and witnesses as possible. These witnesses were not at all vetted and their presentation in court was a facile numbers game; they often relied on vague and self-confessedly poor memories, hearsay, and generic demonological notions.

Tests were also used to determine whether one was a witch. Many of these were based on Daemonologie. One test was to have the accused touch the victim of the alleged wrongdoing. A violent reaction to such contact, or attempts at such contact, confirmed that one was a witch. This test is blatantly fallible. To incriminate the accused did not require corrupt intervention by the witch-hunters and legal officials presiding over the case. It simply required good acting on the part of the accuser, whose vested interest in such falsification was everything that had led them to make the accusation in the first place.

This test at least has one aspect of rectitude in its assumption that there had to be a victim of wrongdoing. This is true to the original form of statutes against witchcraft, which required that the witch had done wrong. We can see this in the words of the 1604 statute, which, in giving its list of synonyms for the felony, forbids the use of “Witchcraft, Inchantment, Charme, or Sorcery”. Such activity was against God and was considered punishable by criminal courts in and of itself. In the 1604 statute, the charge could be enhanced if magic was used to cause injury to persons or damage to things, and this may be considered an expansion of the customary appearance of murder accusations in sixteenth-century witchcraft proceedings.